Jonathan climbed up, using his hands and feet, with his armor-bearer right behind him. The Philistines fell before Jonathan, and his armor-bearer followed and killed behind him.
In that first attack Jonathan and his armor-bearer killed some twenty men in an area of about half an acre.
References for 1 Samuel 14:14
Then panic1 struck the whole army--those in the camp and field, and those in the outposts and raiding2 parties--and the ground shook. It was a panic sent by God.
References for 1 Samuel 14:15