William J. Ross was a Starfleet vice admiral and the senior flag officer in command of Allied military operations during the Dominion War. (DS9: "A Time to Stand", "What You Leave Behind")
During the Dominion War, Admiral Ross coordinated activities from Starbase 375, and was the direct superior of Captain Benjamin Sisko, who also served as his adjutant for a time. He authorized both Sisko's plan to retake Deep Space 9 in Operation Return, and ordered him to command the first Allied strike into Cardassian space, resulting in the First Battle of Chin'toka. (DS9: "Favor the Bold", "Tears of the Prophets")
Admiral Ross was also aware of the activities of the rogue organization Section 31, and even assisted them in placing a mole in the Romulan government in 2375. (DS9: "Inter Arma Enim Silent Leges")
Ross himself led the Allied fleet in the Battle of Cardassia which ended the Dominion War, and presided over the signing of the Treaty of Bajor. (DS9: "What You Leave Behind")
After the Dominion War, Ross became the Bajoran Sector Commander. His flagship was the USS Thunderchild
He assigned Sintina Aurelia to captain the USS Independence. He was also involved in hand selecting the crew for the USS Philadelphia.
His Section 31 'contact' was Morgan.