John Gill Commentary 1 Samuel 13:3

"And Jonathan smote the garrison of the Philistines that was in Geba: and the Philistines heard of it. And Saul blew the trumpet throughout all the land, saying, Let the Hebrews hear." — 1 Samuel 13:3 (ASV)

And Jonathan smote the garrison of the Philistines that was in
Geba
Not the same with Gibeah of Benjamin, as Jarchi; for it can hardly be thought that Jonathan should place himself with his thousand men where the Philistines had a garrison; or that if this was the same with that in the preceding verse, that it should be called by another name in this; but Gibeah and Geba were two places, as Kimchi observes, both indeed in the tribe of Benjamin, and it is very probable not far from one another; see (Joshua 18:24Joshua 18:28) . This seems to be the same with the hill of God, where was a garrison of the Philistines, (1 Samuel 10:5) , who after their defeat by Samuel contented themselves with some strong holds and garrisons in some parts of the land to keep Israel in awe; the Targum understands this of a single person, a governor of the Philistines in this place, whom Jonathan slew, and so Jarchi; and according to R. Isaiah he was one that was appointed to gather the tax for them.

and the Philistines heard of it ,
which alarmed them, and made them prepare for war:

and Saul blew the trumpet throughout all the land ;
not he in person, for he was at Gilgal, as the next verse shows; but he ordered it to be blown, being aware of the preparations the Philistines were making to attack him:

saying, let the Hebrews hear ;
both what his son had done, and what the Philistines were doing.