Several did, but almost all ended in one quitting on their stool, or ending in a stalemate. I don't know of a single 45 round fight going the distance though.
If you have to keep it to 45 rounds only, maybe. Corbett and Jackson went 63 rounds. Tommy Ryan has KO in 48 and 76 rounds Gans beat Nelson via foul in 42 rounds.
Corbett Vs Jackson was a tedious fight with almost nothing happening before it was called unsatisfactory. The 76th round one his opponent quit on his stool. I forgot the Shaugnessy-Ryan fight, but again it was a finnish fight. Did a single 45 round scheduled fight go the distance? I don't know of any.
Corbett and Jackson went 61 rds and the last 30 were a sleepwalk,the spectators sustaining more punishment that the participants!
I hate the misconception that England was about to fall to Germany if we didn't step in. It's simply not true. The German war machine was already struggling with its UK plan, and the UK was starting to gain superiority in the air that it already enjoyed at sea. Germany wasn't invading or conquering England anytime soon.