Denethor I was the tenth Ruling Steward of Gondor, succeeding Dior of Gondor in TA 2435. In TA 2460 the Watchful Peace ended and from that time on the borders of Gondor were constantly threatened, if not openly disputed in war. During the last years of Denethor’s rule the Uruk-hai first issued from Mordor, and in TA 2475 they attacked Gondor, sweeping across Ithilien and completely ruining Osgiliath and its stone-bridge.

Denethor I ruled Gondor for 42 years (TA 2435 - 2477) and was succeeded by his son Boromir I.