Subsequent service Izumo-class cruiser

izumo @ anchor in burrard inlet, vancouver, canada, february 1925

in 1924, 4 of ships 12-pounder guns removed, of qf 2.5-pounder guns, , single 40-caliber 8 cm/40 3rd year type anti-aircraft (aa) gun added. gun had maximum elevation of +75 degrees, , fire 3-inch, 12.5 lb (5.67 kg) projectile muzzle velocity of 2,200 ft/s (680 m/s) maximum height of 23,600 feet (7,200 m). refitted again in 1930–31, torpedo tubes removed of main deck 6-inch guns , casemates plated over; carried 4 12-pounders. @ time, iwate had boilers replaced 6 water-tube boilers, izumo not reboilered until 1935. new boilers produced less steam limited engine power 7,000 ihp (5,200 kw) , reduced top speed 16 knots (30 km/h; 18 mph).

china service , world war ii

izumo @ anchor in huangpu river, shanghai, 1932. american armored cruiser uss rochester anchored left.

in 1932, during first shanghai incident, izumo became flagship of newly re-established 3rd fleet garrisoned japanese-occupied china. 2 years later, equipped operate floatplane @ sasebo naval arsenal. during second sino-japanese war, ship participated in battle of shanghai in mid-1937 during provided naval gunfire support japanese troops ashore.

still in shanghai @ beginning of pacific war on 8 december 1941, izumo captured american river gunboat uss wake , assisted in sinking british river gunboat hms peterel. on 31 december, cruiser struck mine in lingayen gulf while supporting japanese forces during philippines campaign. during period, iwate still serving training ship in home waters. sisters briefly re-classified 1st-class cruisers on 1 july 1942 before became training ships in 1943. izumo returned japan late year , joined sister in training naval cadets.

in 1945, sisters rearmed when 8-inch guns replaced 4 12.7 cm (5.0 in) type 89 dual-purpose guns in 2 twin mounts , 4 of remaining 6-inch guns removed. when firing @ surface targets, type 89 gun had range of 16,100 yards (14,700 m); had maximum ceiling of 30,970 feet (9,440 m) @ elevation of +90 degrees. maximum rate of fire 14 rounds minute, sustained rate of fire around 8 rounds per minute. light anti-aircraft armament reinforced addition of 9 (iwate) , 14 (izumo) license-built hotchkiss 25-millimeter type 96 light aa guns in single, double , triple mounts , 2 13.2-millimeter hotchkiss machine guns in single mounts. 25 mm (0.98 in) weapon standard japanese light anti-aircraft gun during world war ii, suffered severe design shortcomings rendered largely ineffective weapon. twin , triple mounts lacked sufficient speed in train or elevation; gun sights unable handle fast targets; gun exhibited excessive vibration; magazine small and, finally, gun produced excessive muzzle blast. weapon had maximum range of 24,600 feet (7,500 m), effective range 4,900–9,800 feet (1,500–3,000 m).

the sisters attacked, not hit, during american aerial attack on kure in july 1945. however, shockwaves near misses caused extensive flooding in both ships. iwate sank in shallow water on 25 july , izumo capsized 3 days later. both ships removed navy list on 20 november , wrecks raised , scrapped in 1946–47.