He becomes Judge (and warrior–commander) of the Israelites.
According to the Bible, God commands him to deliver Israel from the Midianites and the Amelekites.
Gideon chooses only a small cadre of 300 highly motivated, fearless warriors. (Note: Iconic King Leonidas of Greece will employ a similar stratagem at Thermopylae 675 years later with his immortal “300” (i.e. precisely the same number of warriors).
Gideon is also an important progenitor of “psychological warfare.” Arming his warriors with torches, trumpets and noise–making clay pots, and then attacking at night in full fury, trumpets blaring, torches alit, pots shattering, Gideon strikes fear into the enemy camp. His attacking and surrounding 300 seem to the Midianites like 3,000 and the Midianites retreat across Israel.
After prevailing over Israel’s enemies, master–strategist Gideon nevertheless declines to be king, telling the Jews that God is their ruler.