The British tried some Air defense with Fighters but they were were behind the curve. The French had a level above them and the Germans...ooooff da ! they have tech levels so far out there now it's essentially over.
The British have now deployed flak guns in London and those seem to be more effective than the fiigthers. Time will tell.
Here is a recent shot of an airbattle over the sea hexes on the Portugese coast, it was a devastating setback for me and it hurts me to show this, I sent in my topedo bombers without escort and that was a big mistake. I got a few ships but lots of French production went down in flames as well.

History began July 4th, 1776. Anything before that was a mistake.
Ron Swanson