And the people of Israel again did what was evil in the sight of the LORD, and the LORD strengthened Eglon the king of Moab against Israel, because they had done what was evil in the sight of the LORD.  He gathered to himself the Ammonites and the Amalekites, and went and defeated Israel. And they took possession of the city of palms.  And the people of Israel served Eglon the king of Moab eighteen years.
 Then the people of Israel cried out to the LORD, and the LORD raised up for them a deliverer, Ehud, the son of Gera, the Benjaminite, a left-handed man. The people of Israel sent tribute by him to Eglon the king of Moab.  And Ehud made for himself a sword with two edges, a cubit in length, and he bound it on his right thigh under his clothes.
You really have to read the story of Ehud, the left-handed Benjamite son of Gera, in it’s entirety. I’m going to spread it out over 2 days because the dude is worthy.
Oppression always brings about a revolution of some sort. The Israelites are oppressed by the Moabites at this time, but note the reason why. The people did evil in the sign of the Lord so the Lord strengthened their enemies. For 18 years the people of Israel were subject, both in loyalty and taxes, to the Eglon the King of Moab.
God knows that the best thing for us is to follow Him. We were created, and God called it good, when we live in fellowship with Him. All of our needs and wants find their roots in the living God. When we turn away from Him and seek to be our own lord and our own solution, life is hard. It’s not always the hand of God against us making it hard, sometimes it’s just the created order.
It takes a lot of energy to fight against gravity. Ask anybody that has a skateboard or a rocket ship.
Hebrews 10 says ‘endure hardship as discipline, because God is treating you as sons.’ When I ask my littler kids to help me trim trees and rake leaves, it’s not because I need their help. It’s because they need my help to learn how to work hard and do hard things. They need my help to see the value of helping our neighbors over beating the video games. They won’t learn that on their own.
Israel needed to follow God, so God gave them a little resistance to show them that they weren’t. Ehud rose up out of that. It would have taken some time for him to make that sword. It would have taken time to gather the resources and construct it, and then construct the holder for it that hid under his leg.
It would have taken time, unless he already had this position, to be the guy that was allowed to go pay tribute (taxes) to King Eglon. We don’t know where any of that falls in the 18 years of oppression, but Ehud was the man God raised up to end it.