Even despite the mobility of troops of the late 23rd century, slower and bulkier units still had to be transported by specialised, large-scale craft. This role had been fulfilled for a long time by various models of space planes, but as commercial spaceships became more advanced and resilient, they started to look like a promising alternative to what was essentially just a powerful aircraft. The first Assault Transports, used by Russia in the LW I (First Lunar War) in 2415, were essentially modified mining ships with additional shielding, but only a few years later they were replaced by actual military vehicles. Assault Transports weren't just troop transports: they were also well-armed, fast and relatively cheap to maintain, so with time they found their way to civilian merchant fleets as well.