I kill ... I wound ... I will make mine arrows drunk with blood, and my sword shall devour flesh. Deuteronomy 32:39-42
Jonathan (one of the Machabees brothers) encouraged his company to fight against Bacchides.
Jonathan said to his company: Let us arise, and fight against our enemies. 1 Machabees 9:44
But they were divided by the Jordan River.
And behold the battle is before us, and the water of the Jordan on this side and on that side, and banks, and marshes, and woods: and there is no place of us to turn aside. 9:45
So Jonathan told his troops to ask God for help.
Now therefore cry ye to heaven, that ye may be delivered from the hand of your enemies. And they joined battle. 9:46
And it worked. (I guess.) Jonathan and those that were on his side of the Jordan swam to the other side and together they killed 1000 men in Bacchide's army.
And Jonathan, and they taht were with him leaped into the Jordan, and swam over the Jordan to them: And there fell of Bacchides's side that day a thousand men. 9:48-49
A little later, Jonathan struck the brethren of Odares and the children of Paseron, while his brother Simon discomfited Bacchides, and killed many wicked men that had asked him to come to their country.
Jonathan ... struck Odares, and his brethren, and the children of Phaseron in their tents, and he began to slay, and to increase in forces. 9:65-66
Simon ... fought against Bacchides, and he was discomfited by them: and they afflicted him exceedingly. 9:67-68
He [Simon] was angry with the wicked men that had given him counsel to come into their country, and he slew many of them. 9:69
Thus Jonathan and Simon destroyed the wicked out of Israel.
Jonathan ... destroyed the wicked out of Israel. 9:73
So how may died in this episode?
Well, there were 1000 in Bacchides's army, maybe 100 or so children of Phaseroin, and "many" wicked men (I'll guess 100), for an estimated total of 1200.