Bottom line: God rewards faith with victory.
God tested Gideon's faith when He asked Gideon to thin out the ranks of his army. Gideon dismissed 31,700 soldiers of his 32,000 man army. Gideon reduced his army by faith to just 300 men. After testing Gideon's faith, God then sought to encourage and honor his faith so that ultimately He could reward Gideon's faith with victory. He encouraged Gideon's faith by once again promising him victory. However, this time the promise is in the past tense. The victory is as good as done. He also encouraged Gideon's faith by allowing him to see (hear) a preview of the victory by overhearing the interpretation of a dream. God then honored Gideon's faith because Gideon was faithful. He and his men did what God called them to do (blow, break, shine, and shout) and then they stood in their place. God fought the battle, and Gideon's army experienced the victory.