Nolan Ryan vs. Robin Ventura in 1993.
The batter charged the mound, and for once, a pitcher just kicked the batter's ass. Forget the no hitters and strike outs- this is what made him a legend.
As for true Battles, though not as decisive as those mentioned above, the Battle of Tours was probably one of the great turning points in history. I won't look it up, but I bet the details can be found on the internet somewhere. In about the mid 700's a.d., the Germans defeated the Muslim armies, and prevented the Islamic expansion from continuing to Europe. It was one of the few instances where midevil infantry, with the help of winter cold, defeated cavalry, and thank goodness.