The Germans have one of the most devastating weapons of WWII, the V1-A Rocket (also known as the V1 rocket, or simply the V1). It is shaped like a plane, but functions more like a small missile.
V1-A rocket is an extremly deadly way of bringing down your fortifications into a mountain of burnt debris. When it lands, it explodes into one big explosion, then 4 smaller ones in a line in front of it. If the main blast hits your men, they'll be set on fire. If one of the smaller explosions hits them, they're gibbed. V1s can kill all your units easily if they are grouped close together, and burning survivors can deal even more damage to your defenses by setting everyone else that wasn't harmed by the V1 on fire.
Good news: V1-A's are inaccurate and can be detected by Radar. You should only worry about them if they pass half the screen without blowing up yet.
More good news: You can receive a medal that stops them from spawning.
Even more good news: If you have a very skilled signaler and a radar he can call in Air Superiority, and have Allied Planes intercept the V1. This now works for more than one V-1 Rocket, if there are multiple launched.
Bad news: That medal requires you to receive 2419 V1-A rockets.
More bad news: The the four smaller explosions can be protected against by bunkers and pillboxes, but the main explosion that sets your men on fire cannot be prevented by pillboxes or bunkers.
Horrible News: These terror machines can now come in a blitz wave that launches 5 of them on your position.