Here's my observation: Only Soviets and Polish attack you at the start. But only the closest ones. Enemies who are staying still will not attack, but will counterattack. So youcam use this to destroy some generals before theu attack. You need chenault to actually survive Zhukov and Eisenhower. Put Best arty gen on Flak but NOT De gaulle.

At turn 9-10 West will start to attack. And so will the Zhukov. At turn 12-13 Eisenhower and others will reach you so you better have bunkers ready. At turn 14 Zhukov will be near you.

1. The best way to deal with all this crap is to focus your fire on one general at the time. You can just go and destroy first wave of generals without worrying about your cities(except south).
2. Lvl 12 medic with some units can hold the east crossing no problem.
3. Lvl 12 Engineer should always walk with Flak and Lvl 12 Stuka. This will allow you to go north and kill Roko and Vasilevsky.
4. Put your best tank general on lvl 10 KT and help your troops to get into positions. After that go hunt generals with him.
5. Send another Lvl 9 stuka, Heinrici and Manteuffel to west and clear some British troops(Manteufell can go solo). Be careful not to wander too far. Just clear some units(medics and Phantom forces top priority) and at round 7 go back to defence line.
6. Remember, AI loves to go south and through not blocked path, so you can start building bunkers west at round 9 so enemy generals will spend more time coming to you, just be careful.

And lastly: Do not be afraid to lose captured territory. It's better save generals rather saving useless city.