I once took Washington.
I was going for Sealion, but the initial opening for me sucked, and my opponent defended UK properly. He stacked up against the Germans with Russia recognizing that my odds of surviving with much weren’t good. Since he wasn’t concerned with Sealion anymore, he put everything in the Pacific with the US.
I bought my TTs anyways (I saw something he didn’t) G2. I took out what remaining UK ships there were at the cost of some more planes. There were now no Allied ships in the Atlantic. Still Sealion was going down the toilet now having lost more planes. Still, he still had to buy defensively with the UK.
G3 I moved to Gib with the whole TT fleet loaded with 26 ground units. With my opponent having gone all in on the Pacific side, there were only a few ground units he could put in Washington and every plane he could get there from the Pacific (no match for 26 ground units).
Most importantly, he had NO ships to block my German fleet. G4 it was all over.
Moral of the story, don’t get cocky and turn your back on a power you think is down on its luck. I’ve learned this lesson myself.