As much courage as that raid took and the fact that it led to the Battle of Midway where the Kido Butai (Japan’s mobile strike force which had been kicking the crap out of the Allies) was wiped out, Jimmy Doolittle’s biggest contribution was probably when he took over command of the 8th Air Force.
He ordered the fighters to STOP protecting the bombers....to STOP escorting them closely. Instead their mission would now be to destroy the Luftwaffe. We were willing to incur extra high casualties among the bomber crews for a short time in order to break the back of the Luftwaffe by specifically hunting their fighter planes, and following them down to their airfields and attacking them there if necessary - whatever it took to knock out the German fighters. It worked. After “Big Week” in Spring of 1944 when we attacked Berlin specifically to force them to come out to fight, we destroyed so many Luftwaffe fighters that we had air dominance over Europe after that.
The loss rate for the Bombers went way down and British and American fighter-bombers were free to roam at will over the battlefield.
I had always assumed that infantry had the highest casualty rate in WWII but it turns to have been bomber crews. The German 88 FLAK being an especially dangerous weapon for air crews.
IIRC before we got a foothold on continental Europe fighters didn’t have enough range to accompany bombers to their targets. So even with escorts bombers were vulnerable a good deal of the time.