At the start of the War in the Pacific (1941–1945), Halsey commanded the task force centered on the carrier USS Enterprise in a series of raids against Japanese-held targets.

He felt a "kinship" with his ancestors, including Captain John Halsey of colonial Massachusetts who served in the Royal Navy in Queen Anne's War from 1702 to 1713 where he raided French shipping.

[6] After waiting two years to receive an appointment to the United States Naval Academy, Halsey decided to study medicine at the University of Virginia and then join the Navy as a physician.

Halsey was on the bridge of the battleship USS Missouri on Wednesday, 13 April 1904, when a flareback from the port gun in her aft turret ignited a powder charge and set off two others.

[15] In 1934, the chief of the Bureau of Aeronautics, Navy Rear Admiral Ernest King, offered Halsey command of the aircraft carrier USS Saratoga, subject to completion of the course of an air observer.

This view was challenged when Army Air Corps Colonel Billy Mitchell demonstrated the capability of aircraft to substantially damage and sink even the most heavily armored naval vessel.

When he testified at Admiral Husband Kimmel's hearing after the Pearl Harbor debacle he summed up American carrier tactics being to "get to the other fellow with everything you have as fast as you can and to dump it on him".

In response, on 28 November 1941 Admiral Kimmel ordered Halsey to take USS Enterprise to ferry aircraft to Wake Island to reinforce the Marines there.

Highly anxious of being spotted and then jumped by the Japanese carrier force, Halsey gave orders to "sink any shipping sighted, shoot down any plane encountered".

Instead of returning on 6 December as planned, she was still 200 miles (320 km) out at sea, when she received word that the surprise attack anticipated was not at Wake Island, but at Pearl Harbor itself.

News of the attack came in the form of overhearing desperate radio transmissions from one of her aircraft sent forward to Pearl Harbor, attempting to identify itself as American.

Halsey's skin condition was so serious that he was sent on the light cruiser USS Detroit to San Francisco, where he was met by a leading allergist for specialized treatment.

Prior to the discussion of his raids against the Japanese positions in the Marshall Islands, Halsey informed the midshipmen before him, "Missing the Battle of Midway has been the greatest disappointment of my career, but I am going back to the Pacific where I intend personally to have a crack at those yellow-bellied sons of bitches and their carriers", which was received with loud applause.

Ghormley had been unsure of his command's ability to maintain the Marine toehold on Guadalcanal, and had been mindful of leaving them trapped there for a repeat of the Bataan Peninsula disaster.

It was two days after Halsey had taken command in October 1942 that he gave an order that all naval officers in the South Pacific would dispense with wearing neckties with their tropical uniforms.

[32][33] In November, Halsey's willingness to place at risk his command's two fast battleships in the confined waters around Guadalcanal for a night engagement paid off, with the U.S. Navy winning the battle.

With his determination and grit, Halsey had bolstered his command's resolve and seized the initiative from the Japanese until ships, aircraft and crews produced and trained in the States could arrive in 1943 and 1944 to tip the scales of the war in favor of the allies.

From September 1944 to January 1945, he led the campaigns to take the Palaus, Leyte and Luzon, and on many raids on Japanese bases, including off the shores of Formosa, China, and Vietnam.

The Fast Carrier Task Force was able to bring to battle enough air power to overpower land based aircraft and dominate whatever area the fleet was operating in.

Halsey directed that the Third Fleet "will seek the enemy and attempt to bring about a decisive engagement if he undertakes operations beyond support of superior land based air forces".

The Northern Force of Admiral Jisaburō Ozawa was built around the remaining Japanese aircraft carriers, now weakened by the heavy loss of trained pilots.

Halsey made the momentous decision to take all available strength northwards to destroy the Japanese carrier forces, planning to strike them at dawn of 25 October.

Despite aerial reconnaissance reports on the night of 24–25 October of Kurita's Center Force in the San Bernardino Strait, Halsey continued to take Third Fleet northwards, away from Leyte Gulf.

When Kurita's Center Force emerged from the San Bernardino Strait on the morning of 25 October, there was nothing to oppose them except a small force of escort carriers and screening destroyers and destroyer escorts, Task Unit 77.4.3 "Taffy 3", which had been tasked and armed to attack troops on land and guard against submarines, not oppose the largest enemy surface fleet since the battle of Midway, led by the largest battleship in the world.

When the Seventh Fleet's escort carriers found themselves under attack from the Center Force, Halsey began to receive a succession of desperate calls from Kinkaid asking for immediate assistance off Samar.

[20] Halsey cooled but continued to steam Third Fleet northward to close on Ozawa's Northern Force for a full hour after receiving the signal from Nimitz.

[45] The inquiry found that though Halsey had committed an error of judgement in sailing the Third Fleet into the heart of the typhoon, it stopped short of unambiguously recommending sanction.

Returning home Halsey was asked about General MacArthur, who was not the easiest man to work with, and vied with the Navy over the conduct and management of the war in the Pacific.

Immediately after the surrender of Japan, 54 ships of the Third Fleet returned to the United States, with Halsey's four-star flag flying from USS South Dakota, for the annual Navy Day Celebrations in San Francisco on 27 October 1945.

Upon retirement, he joined the board of two subsidiaries of the International Telephone and Telegraph Company, including the American Cable and Radio Corporation, and served until 1957.