“And after [Ehud] was Shamgar (sword) the son of Anath (answer), which smote of the Philistines six hundred men with an ox goad (sometimes ten feet long, with a pointed end): and he also saved Israel” (Jdg 3:31 RV). Although this is essentially all that is said of Shamgar, there is a major significant point here: The answer to our prayer for salvation is Jesus Christ crucified and pierced with a spear. By His crucifixion, He saves us; by His Word, the double-edged sword, He sanctifies us and guides us. It is also noticeable that nothing is mentioned regarding the land having rest after Shamgar.
After the author mentions Shamgar, he then says, “And the children of Israel again did evil in the sight of the LORD, when Ehud was dead.” It very well could be that Ehud had died prior to Shamgar slaying the six hundred Philistines, and it is mentioned here because Ehud was a major judge and Shamgar, a minor. It could also be that Shamgar killed the six hundred Philistines prior to Ehud dying. The problem with that is: If the land was at rest, why did Shamgar war against the Philistines? A third possibility is that they were contemporaries. Ehud fought against Moab, located to the east of the Promised Land. Shamgar fought against the Philistines, on the west side. When the two are put together, we have Jesus, the Son of God, wholly God and wholly man, crucified, which His redemptive work is the wisdom of God. Christ is the Judge; and, here, He vindicates His people by warring against their enemies, i.e. Satan and the world's ways. --TT