What is your favorite part of history to read/learn about?

IIRC they knew the radar system was helping the British but they had no idea how much. It might have been a totally different world had they kept targeting those stations. Losing focus is exactly how I have pictured it. For all of the success they had in France due to speed and planning, they were all over the map (literally) after that (and thank God)
It also would have been totally different had the Germans began mass production of the ME 262 jet fighter in 1942 when it was ready, instead of mid-late 1944. Engine vibration problems delayed mass production as did top-level Nazi interference.