David had an army of six hundred, but on one occasion, two hundred of them grew weary and could not go on in the battle, and stayed with the supplies. However, after David and the four hundred returned, some did not want to share the spoils with the two hundred,

Now David came to the two hundred men who had been so weary that they could not follow David…So they went out to meet David and to meet the people who were with him…Then all the wicked and worthless men of those who went with David answered and said, “Because they did not go with us, we will not give them any of the spoil that we have recovered, except for every man’s wife and children, that they may lead them away and de
part.” But David said, “My brethren, you shall not do so with what the Lord has given us, who has preserved us and delivered into our hand the troop that came against us. For who will heed you in this matter? But as his part is who goes down to the battle, so shall his part be who stays by the supplies; they shall share alike.” So it was, from that day forward; he made it a statute and an ordinance for Israel to this day (1 Samuel 30.21–25).

Do you see how David viewed the war? He credited the Lord with the victory, even as David credited the victory to the Lord over Goliath. Therefore, it was not so much the four hundred who won, but the Lord, and thus the two hundred also played a vital role, keeping watch of the supplies. David then made it a statute that the fighter and those who support the fighter would share equally in the spoils.