dafeeeeeeeeeesh
The ships enter the atmosphere, one of the ships heads to the river that feeds the city, this particular ship touches down, unloading its troops and a large ammount of some sort of granular material, that proceeds to mix with the water, the animals that drink from it now find that they are knocked out, entering a state alike coma for days.
The other ships hover above the town, then they open their cargo bays and aim their cannons downwards, fiering shells covering the whole area of the town, the shells carry no type of explosive, but they detonate in a violent cloud of knock-out gas, made of a similar component to the material dropped onto the river.
After about 10 minutes, all the ships gather themselves at the edges of the town, encompassing it in a 10-sided shape, they open their baydoors and unload troops onto the ground, they seem to be wearing some sort of plate armor and bearing an assault rifle.