Both ships served in the Pacific Fleet for the duration of their careers, which included an extensive training program during the interwar period of the 1920s and 1930s.

Both ships were present in Battleship Row in Pearl Harbor when the Japanese attacked on 7 December 1941; California was torpedoed and sunk but Tennessee was only minimally damaged.

They both took part in the Philippines campaign in late 1944, and were present at the Battle of Surigao Strait on 24 October, the final battleship engagement in history.

The two ships spent the rest of the war patrolling the East China Sea until the official Japanese surrender in September.

[1] At the same time that European navies had begun to adopt larger guns, they also began to develop longer-ranged torpedoes that could reach well into the expected battle distances of the day, 10,000 to 14,000 yards (9,100 to 12,800 m).

[2] The ships were authorized on 3 March 1915, while design work was still ongoing; tests on the torpedo bulkhead system were completed only in February 1916.

The turbo-electric drive propulsion system that was developed for the Colorados was retroactively applied to Tennessee and California in December 1915, before construction had begun on either vessel.

Under emergency conditions, additional fuel and ammunition could be stored, which significantly increased displacement to 37,948 long tons (38,557 t), which accordingly deepened draft to 34 feet 9.875 inches (10.6 m).

[7][8] The ships were armed with a main battery of twelve 14-inch (356 mm) /50 caliber Mark IV guns[Note 1] in four triple turrets, placed on the centerline in superfiring pairs forward and aft of the superstructure.

[8] Since Tennessee and California were laid down after the Battle of Jutland of mid-year 1916, which demonstrated the value of very long-range plunging fire, their main battery turrets were modified while still under construction to allow elevation to 30 degrees.

[10] The guns suffered from excessive dispersion of shot, which was eventually discovered to have been caused by overly lengthy chambers, which allowed a gap between the shell and the propellant charges.

[13][14] In addition to their gun armament, the Tennessee-class ships were also fitted with a pair of 21-inch (533 mm) torpedo tubes, with one mounted submerged in the hull on each broadside.

[8] They were supplied with Bliss-Leavitt torpedoes of the Mark VII type; these carried a 321 lb (146 kg) warhead and had a range of 12,500 yd (11,400 m) at a speed of 27 kn (50 km/h; 31 mph).

California had an aircraft catapult installed on her aft superfiring turret and she received three Vought UO-1 seaplanes for reconnaissance and fire direction.

Joint training with the Marine Corps provided experience that proved to be useful during the island hopping campaign during the Pacific War.

[21][22] During a period of rising tensions with Japan over the Second Sino-Japanese War in 1940, President Franklin D. Roosevelt ordered the Battle Force to relocate from its homeport in San Pedro, California, to Pearl Harbor in Hawaii in an effort to deter further aggression.

Totally unprepared for the surprise attack, both ships were anchored in Battleship Row, where California was sunk in shallow water.

Tennessee, moored inboard of the battleship West Virginia and thus protected from torpedo attacks, emerged relatively undamaged, though fires from other ships had warped some of her hull plates and necessitated repairs.

[6][21][22] After being freed from Battleship Row, Tennessee steamed to the Puget Sound Navy Yard, where the initial modernization program began.

[22] Tennessee thereafter deployed to the central Pacific to take part in the Gilbert and Marshall Islands campaign, beginning with the Battle of Tarawa in November.

While California was still conducting sea trials, Tennessee next took part in the final stages of Operation Cartwheel by bombarding Kavieng as a diversionary attack.

California was ready for service in time for the Mariana and Palau Islands campaign in mid-1944, and both ships shelled Japanese positions on Saipan, Tinian, and Guam.

[21][22] Both ships had been repaired in time to participate in the next major offensive, the Philippines campaign that began with the invasion of Leyte in October 1944.

Both vessels supported the landing, which triggered the Japanese to launch Operation Shō-Gō 1, a major naval counterattack that resulted in the Battle of Leyte Gulf on 23–26 October.

She provided heavy fire support, targeting Mount Suribachi before and during the Battle of Iwo Jima, before proceeding to Okinawa to conduct the preparatory bombardment of this island for the coming invasion.

She operated off the island for the next month; during the Battle of Okinawa, where the Japanese made repeated and heavy kamikaze attacks on the Allied fleet, Tennessee was hit by one suicide aircraft on 12 April that did little damage but killed more than twenty and wounded more than a hundred.

[21][22][29] The two ships were then assigned to Task Force 95, which was charged with patrolling the East China Sea, with Tennessee as the flagship of its commander, Vice Admiral Oldendorf.

Now too wide to fit through the Panama Canal as a result of their 1943 reconstructions, they were forced to return to the east coast of the United States by way of the Indian and Atlantic Oceans.