All Israel heard say that Saul had struck the garrison of the Philistines, and also that Israel was had in abomination with the Philistines. The people were gathered together after Saul to Gilgal.
Samuel’s departure from the battlefield (1 Samuel 13:15) was symbolic of the breach that now opened up between Samuel and Saul. Saul’s presumptuous plan also failed to bring his departing soldiers back to him.