Who killed an army commander with a tent peg?

Judges 4:21 – [Jael] drove the peg through [Sisera’s] temple into the ground, and he died.

Sisera, commander of the Canaanite army, fled on foot from Mount Tabor after the Canaanites’ attempt to conquer Israel failed. He arrived at the tent of Heber the Kenite, and was offered hospitality by Jael, Heber’s wife.

The Kenites were a nomadic tribe that were related to the Israelites, but also had an alliance with the Canaanites. As Sisera slept, Jael killed him by driving a tent peg through his head.

Jael was lauded as a hero (Judges 5:24–27) because she acted in defence of the Israelites.