Complex sentence: In 1782 the fort was captured by the French, led by La Pérouse; since the English, led by Samuel Hearne, were greatly outnumbered, they surrendered without firing a shot.
Split into simpler sentences: In 1782 the fort was captured by the French, led by La Pérouse. Since the English, under Samuel Hearne, were greatly outnumbered, they surrendered without firing a shot.