Sigh. Lots of answers are incredibly close. Time to give out the answer.
Clue 1: Sejong the Great, George Washington, Duncan, Columbus, Peter the Great (?)
Clue 2: Gettysburg, Hangzhou, Smolensk, Lancaster, Aquitaine
Clue 3: Victory, Pearls (?), Ambush, Ocean, Modern Era (?)
Clue 3...