From the Trivia Files Contest: Here's One for the Soldiers

I thought, in honor of the veterans of foreign wars, and all those who are currently serving, that I would make today's question about a soldier in Israel's history.

Now all the soldiers who are truly celebrated in the Bible were men who fought bravely on the battlefield, but who engaged in an even higher-stakes fight in their personal lives, taking a stand for God.  They sacrificed more than their own strength for a cause; they also were willing to sacrifice relationships with others, even going against the whole nation of Israel, because they believed that the most important battle anyone has ever fought is in the heart.  They weren't just warriors of renown, like Og of Bashan.  They were men of God.

So here's the question for today:

The enemies' camps were so large that their camels were as numerous as sand on the seashore, but this brave warrior, emboldened by a dream and interpretation he'd overheard, and God's assurance of help, led only 300 men to total victory over the invading armies.

                                                        ...Who was he?