To Mars!

In the near future, Earth demands Martian obedience. After Martians rebelled against indentured servitude, their techno-anarchist revolution stopped shipments to earth orbit. But the Martians have to move fast. The window for Hohmann transfer is open, so Earth can afford to send the big ships to Mars. The Martians have retrofitted their small transport ships, called Proas, for war. These small ships have to stop the Earth capital ship from reaching Mars, or it will start orbital bombardment.