The first killing from First Machabees was a terrorist attack, in which Mathathias murdered a Jew who was offering a sacrifice to an idol, along with an officer of the king who happened to be in the area at the time. The author of First Machabees praised Mathathias for the attack, comparing it to Phineas' double murder in Numbers 25.
Mathathias and his friends ... gathered an army, and slew the sinners in their wrath, and the wicked men in their indignation. 1 Machabees 2:44(The text doesn't say who the wicked sinners were, but I suppose any Gentile or Jew who wasn't Jewish enough would do.)
Next Mathathias' mob threw down altars.
And Mathathias and his friends went round about, and they threw down the altars. 2:45And valiantly circumcised all the uncircumcised children they could find.
And they circumcised all the children whom they found in the confines of Israel that were uncircumcised: and they did valiantly. 2:46(According to the story in 1 Machabees, Antiochus had made circumcision illegal, so there were lots of uncircumcised boys running around. Mathathias and his merry men inspected every little penis in Israel to make sure it was properly circumcised, and if not, they cut off the offending foreskin themselves.)
So by slaying the wicked sinners and cutting off foreskins, Mathathias and his mob of terrorist "yielded not the horn to the sinner."
They yielded not the horn to the sinner. 2:48And that's the important thing. Never yield the horn to the sinner.
(The text doesn't say how many wicked sinners were killed by Mathathias' army, so I'll just add another 100 to God's total.)