Judges 11:5

‘ And it was so, that when the children of Ammon made war against Israel, the elders of Gilead went to fetch Jephthah from the land of Tob.'

Recognising the imminence of the coming main attack the elders swallowed their pride, and some went personally themselves to see Jephthah to plead with him to come to their assistance. Here was one trained fighting general who would know how to deal with the enemy. It had been one thing in a fit of zeal to destroy the Ammonite idols (Judges 10:16) and withhold tribute, it was another thing now that war was inevitable and the size of the opposing army had been verified.