One of the themes in the Sublight series is that fisticuffs, be it with space craft of magic or firearms is largely unsatisfying. There may be a winner, but who wins comes down to who had the advantage at the start.

We see this time and again with Active Shooter scenarios. Essentially, any idiot with a firearm can inflict a pile of casualties. At will. For the first few seconds their victims don't even know they are in a scene of carnage. For the next minute, panic causes them to behave erratically. The first time anyone has a chance to respond is when the shooter has to stop to reload. There is really no stopping them. Good guys with guns are either shot down trying to pull out a weapon, are as surprised as everyone else and die in the opening seconds, or panic just like everyone else. There is only a serial murderer and victims. There is nothing glorious in this. These people are sick.

And it's not simply with gun violence. There are active knifer scenarios in other countries. Basically anyone who is primed for violence and has an intent to kill has an advantage in every situation. Basically because the idea that someone is out to kill takes a few seconds to minutes to process for a non-psychopath. Most active shooter training kind of ignores the first few minutes where most people are killed, and focuses on what to do after the killer has to reload.

You start to understand those awful police training scenarios that reinforce that everyone is a psychopath unless proven otherwise. It really is a survival tactic. It's not taught well, WAY over applied to minorities, and WAY under applied to the real sickos if they happen to be white. But there is a glimmer of truth to it.

So... moving on...

Magical Assault

In the world of Sublight, there are no "magic combat". They would be as silly as the scenes in Westerns where two gunman face off in the center of town. In the confines of a movie it can be milked for tension by manipulating the audience's sense of time. In reality... somebody is dead in the blink of an eye. And it's always the guy who draws first with the intent to kill. Yes, it should sound psychotic. It really is.

Sublight Magic can kill, and when it does it is because the caster intended it to. There is no killing curse like Ava Cavadra. Instead, magical assassins utilize some other spell whose effects will kill his or her victim. A lightning bolt spell to electrocute. A fireball spell to burn them to death. Telekineses to rupture a vital artery in the brain. A mind control spell to convince your victim to take their own life. I mean, I think if I wanted to I could do an entire series of books on tracking down magical murders. But that is not what I really want to focus my book on.

There really isn't "combat" with Magic. Just shades of assault with very little the victim can do to defend themselves. You can perhaps devise a defense against one specific attack, but there are SO many different ways to kill someone with Magic that it's pointless.

In the world of Sublight killing someone else with Magic is not really viewed as an impressive achievement. It is considered crass, criminal, and the sort of thing that makes you an outcast from polite society. Well, outside of a war. (But as we all know, killing for the state is entirely different than killing for one's own shits and giggles...🙄 )

For this reason, every police department has a Magical Crimes division. And using Magic to accomplish a caper or murder is considered an aggravating charge. We see that in our own legal system, where bank robbers get extra punishment if they use a gun. We also see it in how minorities get even more punishment than a bank robber if they are somehow caught doing anything while possessing drugs.

Space Combat

I was using my Ship Design Tool to start sketching out the various warships the factions would use. And lo and behold I am finding that in the math the governs space flight, we see the same sort of "mugger" advantage. The party that can pick the time and place of battle wins. Period.

However, if you broadcast your intentions too early, it is possible for your enemy to pick their own time and place that puts you at a disadvantage.

My rules for combat are:

• He who can pick the time and place of battle always wins.
• Two sides entering into combat on equal terms will have a random outcome, down to luck.
• Weapon systems are a lot lighter than armor to protect against them
• A thermonuclear warhead beats 4 aces
• All ships have a common enemy: space. Your opponent's job is simply to let space into your ship.

And on further reflection, many of these rules sounds like something straight out of Sun Tzu's the The Art of War. Replace "chariots" with "assault ships" and "wagons" with "transports" and his advise is still pretty timely.

But his insight is even more prescient when you start looking at the physics of space flight:

With my space vessel calculator, there is nothing more expensive than having to make a return flight without resupply. You have to carry all of the propellent to make the return flight with you, making your launch stage logarithmically heavier.

Let is look at a torpedo. This weapon would be the space equivilent to the Mark 48 torpedo used by NATO today. It has a 450 kg conventional warhead strapped to a guidance system and micronized nuclear engine. If it is launched from a vessel at speed, it simply needs the DeltaV to match velocity with its target. 450kg of payload needs about 40 kg of engines and reactor, and 841 kg of propellent. The total launch mass is about 1331 kg, or ~ 1.3 tons.

He has a big brother. A with a 4500 kg payload. Each mode also has a version that are 2 stage for launching from a space station or planetary surface. They need twice the deltav, because stations or planets aren't moving very fast as compared to spacecraft. This platform has also been adapted into a scientific probe which can travel to a remote part of the solar system and return. That is a 4 stage.

Model	Payload/Warhead	DeltaV	Dry Mass	Wet Mass		Propellent Mass	Propellent:Cargo Ratio
Model 450 - 1 Stage	450 kg	281000 m/s	490 kg	1331 kg		841 kg	1.716
Model 450 - 2 Stage	450 kg	562000 m/s	490 kg	3620 kg		3130 kg	6.388
Probe 450 - 4 Stage	450 kg	1124000 m/s	490 kg	26753 kg		26263 kg	53.598
Model 4500 - 1 Stage	4500 kg	281000 m/s	4892 kg	13298 kg		8406 kg	1.718
Model 4500 - 2 Stage	4500 kg	562000 m/s	4892 kg	36147 kg		31255 kg	6.389
Model 4500 - 4 Stage	4500 kg	562000 m/s	4892 kg	267094 kg		262202 kg	53.598

As we can see, 10 times the payload needs 10 time the fuel. However, the 2 stage versions have to get up to cruising speed, and then turn around and slow back down to their target speed. They need twice the deltaV. And twice the deltaV costs 3.72 as much propellent. It gets worse the more deltaV you need. The 4 stage probe has 4 times the deltaV. So for the same mass of spacecraft and payload to get 4x the deltaV we need 31.23 times the propellent. Because for every stage we basically add up all of the later stages as payload. And, as we have seen, the relationship between the amount of mass we need to propell and the speed we get ourselves up to as a result is logarithmic. Every kilogram of payload we shed is 1.7 kg of fuel we don't have to carry for a single stage rocket, 6.4 kg we don't have to carry for a two stage rocket, and 54 kg we don't need to carry in a 4 stage rocket.

You start to understand why the apollo lander was wrapped in tin foil.

Applying all of this to warfare in space

Now just because warfare is a bad idea doesn't mean people won't do it. I mean hell, we are in the 21st century and we still have to explain to people how to WASH THEIR HANDS and NOT ASSEMBLE IN LARGE GROUPS DURING A PLAGUE. Ignorance would be an actual improvement on the sitation, the Corona Virus has shown us how much actual work people will devote to doing the exact opposite of a good thing.

So let's use the scenario where the "Hero in their own story" (aka the evil) Krasnovians want to invade the planetoid of Psyche. Their up and coming rivals, the Internation Space Treaty Organization, is building a massive new shipyard there. And they are already rolling out new destroyers and cruisers like sausages. While there is some population on the planetoid, there is not much of a military presence. Most of ISTO's defenses are concentrated around keeping the Krasnovians hemmed in on the Moon (where the Krasnovians are based.)

To get to Psyche, Krasnovia has to clear out all of the defensive fleets in between the Earth and Psyche. They also want to knock down any nearby fleets who could plausibly render aid. So they plan a sneak attack. With nuclear weapons. But, if the Krasnovians are known for one thing... well it's being sneaky. But if they are known for two things it is... well for being over-planner. And technophiles.... Ok somewhere around 9 or 10 on the stereotypes for Krasnovians is "penny pinching".

Model	Payload/Warhead	DeltaV	Dry Mass	Wet Mass		Propellent Mass	Propellent:Cargo Ratio
Model 450 - 1 Stage	450 kg	281000 m/s	490 kg	1331 kg		841 kg	1.716
Model 450 - 2 Stage	450 kg	562000 m/s	490 kg	3620 kg		3130 kg	6.388
Probe 450 - 4 Stage	450 kg	1124000 m/s	490 kg	26753 kg		26263 kg	53.598
Model 4500 - 1 Stage	4500 kg	281000 m/s	4892 kg	13298 kg		8406 kg	1.718
Model 4500 - 2 Stage	4500 kg	562000 m/s	4892 kg	36147 kg		31255 kg	6.389
Model 4500 - 4 Stage	4500 kg	562000 m/s	4892 kg	267094 kg		262202 kg	53.598

Now, if you had the choice of lobbing nuclear missiles from the Moon, or from a ship which makes more sense? As we can see, our Model 4500 in the ship launched configuration is 1/3 of the mass of the surface launched. But it requires a ship to act as its first stage, and lob it roughly in the trajectory of the target. How big would that ship have to be?

So let us say they build something akin to a ballistic missile submarine in our world. Fast, stealthy, and with manned crew of about 160. I'm basing the concept on the Typhoon class submarine. But, done in space. We'll say it carries 20 torpedos (for self-defense), and 20 strategic missiles. The 20 torpedos have a mass of 26620 kg and the strategic missiles 265960 kg for a combined weapons payload of 292.6 metric tons. When I build a habitat for 160 people, and slap all of the comforts of home for a 120 day voyage, the vessel comes in with an empty mass (minus propellent and cargo) of 1576.4 metric tons. So about 1284 tons more than the the weapons it is carrying. All told the "dry mass" of the vessel is about 1800 metric tons.

However, this is one of those infamous 4 stage journeys. The vessel has to infiltrate hostile space, patrol, and return. For an attack mission, we can assume that all of the ordinance will be dropped. So that saves us some fuel. But the vessel has a launch mass of 102,000 metric tons. A typhoon class submarine displaces 25,000 tons on the surface and 48,000 tons submerged. This ship is more comparable in mass to a Nimitz class aircraft carrier. But it travels at a million kilometers per hour, and can cover the twice the distance from the Earth to the Sun in 12 days. (And make a complete round trip in 30!).

But let us drop that speed in half. If we are stealthy and sneaky, and we have 120 days worth of supplies, why do we need so much speed? I mean, isn't 500,000 km/hr fast enough. When I drop the deltaV to 100,000 m/s we get a much more economical vessel. The same dry mass, but the wet mass is 7,760 tons. This is about 1000 tons lighter than a Arleigh Burke class destroyer in our world. The tradeoff for this economy is round-trip time of 70 days.

The model file for my "Red October" is here.

How does that 35,000 tons stack up against simply making those 40 torpedo and missles of the 2 stage variety? 20 of each of the two stage varieties of the same weapons would have a combined mass of 989 metric tons. From a purely economic perspective, it's not great. But, perhaps, there are technical difficulties that make putting a launch vehicle in the neighborhood a requirement.

Now if we can't rely on stealth, we may need to look again at the speed. If we really want to deliver our payload in a fornight we need to pare down our launch platform a bit. A Typhoon is a boomer. Go deep. Stay out. Be silent. Lets make our next ship like more like an Alfa class. Fast. Light. Highly automated. And let's make it's mission focus on ground attack. It operates like a bomber, just there, and back, and no need to keep the crew on board any longer than we need. It uses an advanced propulsion system that provides a Ve of 350000, which pushes up our cruising speed. So a mission endurance of 30 days. Well give it 12 missiles and 4 torpedos for a payload of 164900 kg.

This vessel is much, much lighter. However this is down to a much more spartan accommodation, a very lightweight construction, and only carrying enough supplies for 30 days. It's cruising speed is 1.25 km per hour. It can fly 2 Au, and back, in 24 days. It can deliver it's payload on target in 15 days.

Model	Payload	DeltaV	Dry Mass	Wet Mass		Propellent Mass	Propellent:Cargo Ratio
Red October	292.6 mt	100000 m/s	1800 mt	7760 mt		5960 mt	3.31
Beta	164.9 mt	562000 m/s	246 mt	13435 mt		13189 mt	53.61

As we can see there is a premium on speed, and a premium on being able to make a return trip on your own supplies. Sea going vessels have similar tradeoffs in our own world. The US and British navies have a long history of operating at a distance. And they utilize underway replenishment. In days of old, they would establish coaling stations on strategically placed islands where vessels could pick up coal and fresh water and food. And, given the cramped quarters and slow pace of ships back then, let the crew out to stretch their legs.

But then the question has to be asked, where do these supplies come from? Why from other ships. But those ships can be dedicated to strictly carrying cargo and can operated at a much slower tempo. Like in space, you pay for speed with fuel. The US Navy doesn't even use islands anymore. They have perfected using a big supply ship that can "dock" one or two other vessels at a time.

In the world of Sublight, operating indefinitely in space is ISTO's bailiwick. All of their colonies are on asteroids. But that is not to say the Krasnovians can't learn a thing or two.

Our Krasnovians are going to want to land a few thousand troops at a time if they are going to take Psyche. And in addition to the troops themselves, the Krasnovians are going to need weapons, and landing ships, and all of the other "comforts of I'm stealing your home." These needs are sort of niche, so it's not good just swiping a few cruise liners and pressing them into government service. Well...

The Black-Star line runs regular service between the Earth system and the Asteroid belt. Or rather, they ran regular service. Their longest trips are around 2.5 au, but they do try run them when the planets/asteroids/etc are in alignment. They have a class of ships that carry roughly 3000 passengers and crew, and about a 30,000 metric tons of cargo. To keep costs down, they really keep their speed down. And they also really pack 'em in as far as passenger "comforts".

The line also run a pure-cargo version of the same platform of vessel, with a crew of 24. Cargo runs at a lower deltav, making the 2.5 AU trips in 90 days instead of the Britanica's "speedy" 60 days. Both ships operate using commercial propulsions systems that are bulkier, heavier, and not as efficient as the ones used in military vessels. (But they do keep the costs down...)

Model	Payload	DeltaV	Dry Mass	Wet Mass		Propellent Mass	Propellent:Cargo Ratio
Britannica	3000 mt	120000 m/s	19571 mt	38852 mt		19281 mt	0.99
Amazon	45000 mt	80000 m/s	48200 mt	76136 mt		27936 mt	0.58

Each of them are only built for a one-way trip. A round-trip version of each would look like:

Model	Payload	DeltaV	Dry Mass	Wet Mass		Propellent Mass	Propellent:Cargo Ratio
Britannica (return with empty load)	3000 mt	240000 m/s	19571 mt	71262 mt		51691 mt	2.64
Britannica (return with full load)	3000 mt	240000 m/s	19571 mt	77129 mt		57558 mt	2.94
Britannica (return / passengers only - no cargo)	0 mt	240000 m/s	16571 mt	65306 mt		48735 mt	2.94
Amazon (return with empty load)	45000 mt	160000 m/s	48200 mt	79066 mt		30866 mt	0.64
Amazon (return with full load)	45000 mt	160000 m/s	48200 mt	120260 mt		72060 mt	1.5
Amazon (light load return empty)	19281 mt	160000 m/s	22481 mt	38440 mt		15959 mt	0.71
Amazon (light load return full)	19281 mt	160000 m/s	22481 mt	56092 mt		33611 mt	1.5

A two-way trip is far too costly to operate for the cruise liner. For a one-way trip it costs about 0.99 kg of propellent for kg of ship/cargo/passenger. For the return trip it costs 2.64 kg of propellent. The ship is also 300 tons heavier to carry the extra provisions for those on board. Even if we ditch the cargo for a round-trip run, we are still using far, far more propellent than if we could simply go somewhere, dock, and refuel.

For the cargo ship, without cargo it doesn't have that much mass. Sending a cargo ship on a round trip, assuming it is coming back empty, is about 3000 tons of fuel. Not ideal. But not all that terrible. Returning with cargo on a round trip does get you into the realm where it requires 1.5 kg of propellent to get 1 kg of ship somewhere. And that is the case, even when you run the ship light. You are just pushing fewer kilograms of ship.

The head scratching thing is that it's actually cheaper to ship fuel on an Amazon to a stranded Britannica than it would be for the Britannica to carry it's own return fuel in extra tanks. The cost of a complete Amazon flight (at least in terms of propellent) to drop off the 19000 tons of propellent that a Britannica needs for a one way trip is 16000 metric tons. And that includes the fuel for the return flight of the Amazon.

Now, you will have to plan ahead. An Amazon of far, far slower than even a lumbering Britannica. But it would be relatively doable to operate a convoy of mega-tankers to keep a remote base supplied. You just have to either send them far enough in advance, or run a steady stream of them. Who cares if a shipment takes 90 days to arrive, if they are spaced 2 weeks apart?

We know bring you back to your regularly scheduled invasion...

As you can see, though, commercial ships lack the performance needed to deliver combat troops in a timely basis. 60/90 days is an eternity in warfare. But we have learned that it is better to have a ship refueled on station for a return trip than make it lug its fuel with it. Secretly for the past decade, the Krasnovian empireRepublic has been building an armada of invasion ships.

This design is based roughly on the America class assault ships used by the US Navy. Each carries ~1800 marines into battle, and has a crew of 1000. It also has some self-defense weapons, and embarked assault and landing craft. It was designed using proven (read that slightly old-tech) LiD fuel. And they don't intend to use these very often, but when they do they need to run hell-bent for leather. Their fuel efficiency leaves a bit to be desired. But they can deliver troops across 2 AU in 14 days. It can operate at a more pedestrian rate if fuel supplies need to be conserved. If you run it at the same speed as the tranports, it costs a fraction of the fuel to run.

Krasnovia designed, along side the Amerika, a replenishment vessel for the fleet. The Europa class is a military bulk carrier platform. It utilizes a high-tech propulsion system (muon-catalyzed deuterium-deuterium) that provides both a massive VE (500000) and allows it to be powered by simple heavy water. (Most other high performance engines use Lithium-Dueteride.). Despite the massive effective velocity of the propellent, they don't run it at a very high deltaV, because it's job is mainly to deliver cargo in an energy (and fuel efficient) manner. It will take 24 days to reach a destination that is 2 AU away. It needs that efficiency because it needs to make round trips. It is the one bringing fuel to the vessels that need it.

This combination of slow (as much as a million km/h is slow...) and high efficiency engine allows the much larger Europa to deliver 100,000 tons, and return home empty, for less propellent than the Amerika uses for a one-way trip. If need by, it can run faster. You are just going to pay for that speed with increased energy costs. They only run high-speed loads at 25% of cargo capacity because the mass of the extra fuel would be too much for the structure of the vessel to support with a full load of cargo.

Model	Payload	DeltaV	Dry Mass	Wet Mass		Propellent Mass	Propellent:Cargo Ratio
Amerika (full deltav)	300 mt	562000 m/s	10898 mt	80530 mt		69632 mt	6.390000000000001
Amerika (half deltav)	300 mt	281000 m/s	10898 mt	29624 mt		18726 mt	1.72
Europa (normal speed)	100000 mt	500000 m/s	153936 mt	197658 mt		43722 mt	0.28
Europa (full bore)	25000 mt	2000000 m/s	37080 mt	190093 mt		153013 mt	4.13

The big day

The model file for my "Beta" is here.

So, the Krasnovians got all of their devious plans together from 1960 to 1962. In that time they constructed a dozen Amerikas. They staged Beta and Red Octobers in orbit around Mars. Their conventional fleet of destroyers and cruisers would escort the landing ships. All they needed was a decent alignment of Earth and Psyche. And on February 11, they had a perfect setup. ISTO's main fleet was located in the Inner System. Most of their forces were concentrated at their base on the asteroid Cruithne. A squadron was also located on Earth's L4 and L5 Lagrange points. They needed to be eliminated because the too could dispatch ships that could catch the invasion armada. Eros and Ryugu were targeted because they contained major shipyards of staging posts. Their destruction would also mask Krasnovia's true goal.

The surprise attack portion of their plan worked perfectly. Their stealthy craft maneuvered to their attack trajectory. Each released their weapons with split second precision. Each warhead hit its destination nearly simultaneously. ISTO's ability to mount an immediate counter-attack was non-existent.

However, the large Armada thrusting along a straight line to Psyche was a sure-fire tell. While ISTO did not have much in the way of conventional forces, they did have a tremendous arms cache. Conventional thinking at the time said that Krasnovia's fleet would have really only been under threat during the last few minutes of their deceleration burn. That conventional they would be moving too fast to intercept at every other point.

Leaders on Psyche did realize while the Krasnovian fleet was moving along at a pretty good clip, they had picked up too much momentum to be able to manuever. This made their flight path easy to predict. And while ISTO may not have had a lot of warships at their disposal, they did live in an asteroid belt. And with enough explosives, set off in just the right way, you can pulverize the asteroids and aim the debris. They didn't even have to be moving all that fast, the speed of the Krasnovians was more than enough to obliterate them. And they weren't content to leave it up to just asteroids. They also fired every ballistic projectile the had in inventory. That's the beauty of space. Once things start moving, they don't stop until they hit something.

Also helping matters was that Psyche had 14 days to plan all of this.

When the Krasnovians moved through that part of space, only a few ships were hit. As they exploded, their debris impacted other ships. And the pattern continued until there was not a Krasnovian vessel that wasn't at least crippled by the time they reached Psyche. Attempts at rescue were made more difficult by the clouds of debris. Many ships were disabled before they could complete their deceleration burn. Some impacted with Asteroids. Some continued sailing out of the Solar System. Nobody likes to dwell on what became of anyone who found themselves marooned on a derelict vessel.

Nobody looks back on the war of 1962 as "glorious." They remember the dead. They remember the foolishness. People are remembered for doing their duty. But neither side looks back at those events as "victory." ISTO fleet was destroyed in port by a surprise attack. Krasnovia's fleet was destroyed by space junk and wildly fired bullets.

In the aftermath ISTO abandoned any thought of staging forces in the Inner system. Both ISTO and Kransovia sat down to work out a deal that would let both of them get what they really wanted. ISTO moved out of Krasnovia's backyard. Krasnovia got the rights to settle the moons of Jupiter and Saturn (with the option to take Uranus and Neptune). The tragedy is that all of that could have been worked out before hand. Instead two fleets were utterly destroyed, and hundreds of thousands of people died.

And for good measure, several chunks of the Solar System were also now clogged with debris. They continue to be a hazard to navigation today.