Summary: The period of the judges is characterised by cycles of idolatry, punishment through subjugation by foreign kings, followed by periods of deliverance and freedom lead by each judge. The first judge to rule over the people was Otniel the son of Kenaz and nephew of Calev who brought forty years of tranquillity to the people. Ehud followed Otniel who fought off eighteen years of Moabite oppression by killing Eglon the Moabite king.
A deeper look: Ehud is described as ‘a man with a closed right hand’ (Judges 3:15) meaning simply that he was left-handed (Radak loc. cit.). This was significant in his assassination of Eglon whose oppression of the Jewish people had become unbearable. Ehud concealed a double-edged dagger in his garments on his right thigh so it would be easy to extract with his left hand (Metzudat David loc. cit.).
After bringing a tribute to present to Eglon, Ehud informed the king that he had brought a secret message from God. Eglon arose from his throne to hear the message and at that moment, Ehud seized the dagger with his dominant left hand, thus taking Eglon by surprise. He thrust it into Eglon’s belly until the fat closed around the hilt, ending eighteen years of bitter oppression.
The Midrash Tanchuma (Vayechi 14) describes a Torah scholar as a cherev pifiyot, a double edged sword for those who study Torah derive nourishment from both the physical and spiritual worlds. While Ehud used the most practical weapon, it also signified that the Jewish people, who had lost their connection to Torah, were saved through Torah.
The Midrash comments further that despite being wicked, Eglon was rewarded for rising from his throne out of respect for God, in order to hear the prophecy brought by Ehud. For this one act he merited righteous descendants through Ruth, the great-great-grandmother of King Solomon. The Gemara goes further mentioning the merit of Eglon’s ancestor, the wicked Balak who nonetheless brought sacrifices to God, although not for the sake of Heaven (Numbers 23:29). This teaches us that it is better to perform God’s commandments even without the right intent, than not doing them at all. The act of doing them no matter what, will eventually inspire us to perform them for the sake of Heaven (Sotah 47a).