The Battle off Samar was the centermost action of the Battle of Leyte Gulf, one of the largest naval battles in history, which took place in the Philippine Sea off Samar Island, in the Philippines on October 25, 1944. It was the only major action in the larger battle in which the Americans were largely unprepared. After the previous day's fighting, the Imperial Japanese Navy's First Mobile Striking Force, under the command of Takeo Kurita, had suffered significant damages and appeared to be retreating westward. However, by the next morning, the Japanese force had turned around and resumed its advance toward Leyte Gulf. With Admiral William Halsey Jr. lured into taking his powerful Third Fleet north after a decoy fleet and the Seventh Fleet engaged to the south, the recently-landed 130,000 men of the Sixth Army were left vulnerable to Japanese attack on Leyte.

Kurita, aboard the battleship Yamato, took his large force of battleships, cruisers and destroyers from the San Bernardino Strait and headed south toward Leyte, where they encountered Task Unit 77.4.3 ("Taffy 3"), the northernmost of the three escort carrier groups under Rear Admiral Clifton Sprague that comprised the only American forces remaining in the area. Composed of only six small escort carriers, three destroyers, and four destroyer escorts, Taffy 3 was intended to provide shore support and anti-submarine patrols, and did not have guns capable of penetrating the Japanese armor. The Japanese opened fire shortly after dawn, targeting Taffy 3's escort carriers, which Kurita mistook for the main carriers of the Third Fleet. The escort carriers fled for the cover of rain squalls and launched their aircraft in defense, while the three destroyers and destroyer escort USS Samuel B. Roberts, led by USS Johnston, launched a torpedo attack that sank one ship and sent the Japanese strike force into disarray.

Japanese aircraft from the base at Luzon launched kamikaze attacks on the retreating American task force, sinking one escort carrier and damaging three others. With Taffy 2's aircraft joining the battle, the increasing severity of the air attack further convinced Kurita that he was engaging the Third Fleet's surface carriers. Satisfied with sinking what he believed were multiple carriers and worried the bulk of the Third Fleet was approaching, Kurita withdrew his fleet north, having failed to carry out his orders to attack the landing forces at Leyte Gulf.

Taffy 3 sustained heavy losses in the action, losing two escort carriers, two destroyers, a destroyer escort and numerous aircraft. Over 1,000 Americans died, comparable to the combined losses of American men and ships at the Coral Sea and Midway. Three Japanese cruisers were sunk by air attack, and three others were damaged. The Japanese had over 2,700 casualties. Taffy 3 was awarded the Presidential Unit Citation and Captain Ernest E. Evans of the sunk Johnston was posthumously awarded the Medal of Honor. Fleet Admiral Chester W. Nimitz wrote afterwards that the success of Taffy 3 was "nothing short of special dispensation from the Lord Almighty." The Battle off Samar has been cited by historians as one of the greatest last stands in naval history.