Its well known that any scientific development or discovery is quickly exploited for military purposes, and the hovercraft industry is not different from any other in that respect. In general, an air cushioned vehicle cannot change direction very quickly, so would be no good in a combat situation for example, but the fact that it rides on a cushion of air without touching the surface of the ground raises very interesting possibilities.
Imagine a military commander needing to transport men and equipment many miles over marshy terrain, sometimes hard ground, sometimes shallow water and in places a sticky mud. The variety of surface conditions requires a mode of transport that isn't land based, nor marine in nature. A hovercraft simply glides over any surface and the flatter the better. Water, mud, slippery ice and snow are no obstacles to a hovercraft.
Although the principle of using a contained air pressure as a means of transport was known for decades, it was mostly seen as a novelty having no real commercial value. After all, steering the craft was difficult. It couldn't stop very quickly, or manoeuvre tight corners, but then neither could large ships. In fact, sea travel was the most interesting early application of ACVs, both for private commerce and the military.
After World War 2, Russian hovercraft manufacturers built an enormous craft, possibly still the largest in the world, which could carry hundreds of tons of men and machines. Russia is of course a vast country with plains and ice which are easy to traverse using a vehicle that hovers just above the surface. It's not how nimble the craft is, but it's carrying capacity for this type of work. It doesn't get bogged down because it has no wheels. If it cannot stop quickly then it's relatively easy to allow more time to stop, it's a simple as that! A bit of planning will ensure that the terrain to be hovered over has plenty of space for turning.
The engines used for thrust and lift are of course much bigger than a comparable size commercial hovercraft. In fact, the supersized model has many engines. If you think about it, military vehicles of all kinds are always much heavier than regular machines, due to the fact they they are intended for rough and frequent use. It's also true that military hovercraft maintenance schedules are second to none, so that the motors are always in tip-top condition.
Specialist training is required to pilot such a craft. It isn't an aircraft, marine craft or land vehicle therefore a different approach has to be taken to controlling direction and speed.