Information about the first cycle is found starting in 3:7 - "So the children of Israel did evil in the sight of the LORD. They forgot the LORD their God, and served the Baals and Asherahs. Therefore the anger of the LORD was hot against Israel, and He sold them into the hand of Cushan-Rishathaim king of Mesopotamia; and the children of Israel served Cushan-Rishathaim eight years. When the children of Israel cried out to the LORD, the LORD raised up a deliverer for the children of Israel, who delivered them: Othniel the son of Kenaz, Caleb's younger brother" (3:7-9). Their deliverance was not an accident; Got prepared Othniel for the task. Othniel prevailed over the Mesopotamians and freed Israel from their oppression. For 40 years, the Israelites were free and blessed again. But, then Othniel died and the nation drifted into immorality once more.
The second cycle begins as follows:
"And the children of Israel again did evil in the sight of the LORD. So the LORD strengthened Eglon king of Moab against Israel, because they had done evil in the sight of the LORD. Then he gathered to himself the people of Ammon and Amalek, went and defeated Israel, and took possession of the City of Palms. So the children of Israel served Eglon king of Moab eighteen years. But when the children of Israel cried out to the LORD, the LORD raised up a deliverer for them: Ehud the son of Gera, the Benjamite, a left-handed man. By him the children of Israel sent tribute to Eglon king of Moab" (3:12-15).
The suffering of Israel was no accident; God prepared Eglon for the task of punishing His people. Israel served Moab for nearly 20 years (i.e., they paid taxes to the Moabites for peace). When the Israelites cry out in repentance, God hears and prepares another judge to save them. Ehud was a man of courage. He took tribute money to Eglon and deceived the king into being alone with him. Ehud then delivered "a message from God"--namely, a dagger about 18 inches in length thrust very deeply into the king's fat belly. Eglon died; Ehud escaped stealthily. Ehud then led the Israelites in at attack against the Moabites and killed 10,000 of their mighty warriors. This freed Israel once again, and they enjoyed peace for 80 years before drifting again.
Not much information is given in regards to the third cycle - "After him was Shamgar the son of Anath, who killed six hundred men of the Philistines with an ox goad; and he also delivered Israel" (3:31). Evidently the Philistines had oppressed the Israelites for a period of time, but the third judge--Shamgar--put a stop to it with God's help and an ox goad (i.e., an 8' long rod with a sharp end to poke oxen in a desired direction).
There are several lessons to be gleaned from what we have considered thus far: