And, behold, Saul came after the herd out of the field; and Saul said, What aileth the people that they weep? And they told him the tidings of the men of Jabesh.
1 Samuel 11:5 KJV COMMENTARY https://bible.com/bible/1/1sa.11.5.KJV
Sauls kingdom was still new and he was still following after the herd and yet so humble. https://bible.com/bible/1/1sa.11.5.KJV
And the Spirit of God came upon Saul when he heard those tidings, and his anger was kindled greatly. And he took a yoke of oxen, and hewed them in pieces, and sent them throughout all the coasts of Israel by the hands of messengers, saying, Whosoever cometh not forth after Saul and after Samuel, so shall it be done unto his oxen. And the fear of the LORD fell on the people, and they came out with one consent.
1 Samuel 11:6-7 KJV COMMENTARY https://bible.com/bible/1/1sa.11.6-7.KJV
Saul acted based on the spirit coming upon him and because of that anointing his fear fell upon the people and they followed him.
Just as Samuel had told him… “do as occasion serves”
Now here was an occasion and God was with him https://bible.com/bible/1/1sa.11.6-7.KJV
And he took a yoke of oxen, and hewed them in pieces, and sent them throughout all the coasts of Israel by the hands of messengers, saying, Whosoever cometh not forth after Saul and after Samuel, so shall it be done unto his oxen. And the fear of the LORD fell on the people, and they came out with one consent.
1 Samuel 11:7 KJV COMMENTARY https://bible.com/bible/1/1sa.11.7.KJV
If THE Spirit of God is upon a man 👨, that man can gather for the kingdom of God.
God here put fear upon the people and it caused them to join Saul in battle.
This is not the first time the spirit of God has come upon a man for him to gather God people for war and for service.
We see it in Gideon also and many other judges. https://bible.com/bible/1/1sa.11.7.KJV
And the people said unto Samuel, Who is he that said, Shall Saul reign over us? bring the men, that we may put them to death.
1 Samuel 11:12 KJV COMMENTARY https://bible.com/bible/1/1sa.11.12.KJV
Now the evidence of his calling and anointing was seen.
Now there was zest in the tone and approach of the people https://bible.com/bible/1/1sa.11.12.KJV
Then said Samuel to the people, Come, and let us go to Gilgal, and renew the kingdom there.
1 Samuel 11:14 KJV COMMENTARY https://bible.com/bible/1/1sa.11.14.KJV
So really not all the people had accepted Saul as king 👑.
Let’s not forget that at such a time when a new kingdom is being established, there are varied interests and factions.
Samuel’s influence both spiritual and through years of judging backed Saul.
But that was not powerful enough to ensure acceptance by the whole nation.
But now that heaven had responded by helping Saul to gather the people for war, he had expanded his authority and influence.
He had a standing army with victory ✌️, spoils of war and weaponary on their side.
Now he was king indeed. This was a fine opportunity to consolidate his authority and kingship and this Samuel did at gilgal.
The next question 🙋 however is, why gilgal
Dakes commentary explains that it was at gilgal that they first entered canaan so it was befitting in that regard to go renew the kingdom where it all started from. https://bible.com/bible/1/1sa.11.14.KJV
And all the people went to Gilgal; and there they made Saul king before the LORD in Gilgal; and there they sacrificed sacrifices of peace offerings before the LORD; and there Saul and all the men of Israel rejoiced greatly.
1 Samuel 11:15 KJV COMMENTARY https://bible.com/bible/1/1sa.11.15.KJV
So his kingdom was strengthened further for proof of his calling was bare for all to see https://bible.com/bible/1/1sa.11.15.KJV