Considering the gracious leading and patience Gideon had received from God while in preparation for the great battle, it might seem ironic that Gideon would threaten (and carry out) such severe punishments on the residents of Succoth and Penuel for refusing to supply him and his men while they were pursuing the Midianites.
15He came to the men of Succoth and said, "Behold Zebah and Zalmunna, concerning whom you taunted me, saying, 'Are the hands of Zebah and Zalmunna already in your hand, that we should give bread to your men who are weary?'" 16He took the elders of the city, and thorns of the wilderness and briers, and he disciplined the men of Succoth with them. 17He tore down the tower of Penuel and killed the men of the city (Judges 8:15-17, NASB)
To help understand this, let’s take a look at the scene. First, we see Gideon and his 300 men (note that none had been killed because God was with them), crossing over the Jordan in pursuit of the Midianites. The enemy still fielded a sizable force of 15.000 men, even though 120,000 had fallen from internal fighting and at the hands of the combined forces of Israel that were mustered after the battle began.
Nevertheless they were fleeing before Gideon. The retreating enemy would have been visible to both Succoth and Penuel, even though it may have seemed to them like a vast pride of lions was being pursued by a little flock of goats.
Even so, the men of both cities responded to Gideon’s request for assistance, not with reluctance or even cautious aid, but with taunts. These were Israelites refusing help in the battle or even aid to their countrymen who were in harms way. While they may have believed they were preserving their cities by remaining neutral in the conflict, they actually became collaborators with the enemies of Israel. As a result, after the battle was won, the elders and men of Succoth and Penuel shared, in some measure, the lot of the enemy.