'Wartime' in the Bible

"Furthermore, you're aware of what Zeruiah's son Joab did to me and to those two commanders of the armies of Israel, Ner's son Abner and Jether's son Amasa, whom he killed, and how he shed the blood of wartime during times of peace, staining the very belt he wears around his waist and the sandals he wears on his feet.