Ingold was a Man of Gondor and a soldier of the realm.
During the War of the Ring, he was the guard of the seven doors captain and he was in charge of a group soldiers manning the northern gate at the Rammas Echor just before the start of the Siege of Gondor. He allowed Gandalf and Pippin through, he recognized the wizard immediately but he enquired after Pippin's business in Minas Tirith since he didn't thrust foreigners and the hobbits were completely unknown to him.
Days after Gandalf had passed, an army out of Mordor (east) crossed the river Anduin and descended on Ingold's position. He retreated with his men back to the city, reporting that the northern road had fallen into the hands of the enemy. This was woeful news in Minas Tirith, because it was thought to mean that the Rohirrim could not come to their aid (though in fact the Riders were able to find another route, the long-forgotten Stonewain Valley).