Chantel Yang's 5-2 win in epee clinched Commack's 14-13 win over Ward Melville, snapping the Patriots' 195-match win streak in girls fencing Tuesday.
Ward Melville had not lost since the 2000-01 season.
"It's an unbelievably incredible moment for us," Cougars coach Rob Raeihle said. "We have been a competitive team for years, but it's always been in the shadow of Ward Melville ... We've always had the skill and the ability, and they truly believed that this could happen."
Yang went 3-0 overall in epee for Commack, which is 7-0 in League I. Samantha Abbott also went 3-0 in epee and Erin O'Neill 2-1 in epee. Gaby Musto went 2-1 in sabre and freshman Stephanie Miller won Commack's first sabre bout.
"We had to win three in a row to finish it off and it took every kid on our team to make this happen," Raeihle said. "We did everything today."