Touchwood is correct, military freebies are rather hard to find. George (zippy?) has a nice wrecked building - kinda like the old airfix one. You could try using ones from a flight simulator - but the poly count and detail will be very low, plus you'll need to re-texture. 

Which really leaves you with commerical stuff.

Apart from the 'squid - where I also see your post (good idea) -theres a few bits here, AH3D's stuff is nice. Poserworld has a reasonable lanc if you're a member there. Bazze has given away a few free planes, Spit, 109, and theres a free spit at possetteforever if you can get past their bizzare signup process.

Poserworks has a P40 warhawk and other WW2 planes - average prices around $35.  DeEspona is about the only person who's made a large military collection - max format - and Vanishing Point is carefully converting them to Poser.

Waves at Touchwood - we last meet at the Imperial War Museum :)

Pinky - you left the lens cap of your mind on again.