USS White River: How the US Navy transformed a landing vessel into a legendary rocket artillery ship

‘Rocket ships’

USS White River’s design was the product of an evolving way to address the needs of shore bombardment during World War II.

Allied assaults on the beaches of the Pacific, Africa, and Europe had proved the need for massive firepower to destroy fortified fighting positions and minefields. The deck guns of battleships, cruisers, and even destroyers were sometimes too slow to provide accurate fire or too powerful in the immediacy of troop landings.

The best solution was, for lack of a better term, rocket ships: Small vessels porcupined with rocket launchers able to fire dozens or even thousands of rockets en masse.

Rather than building an entirely new vessel, it was decided to modify medium-sized landing ships (classified as LSMs for ‘Landing Ship Medium’). Originally designed to carry troops, vehicles, and supplies directly onto beachheads, the vessels proved to be quite versatile, with many models being reconfigured for various uses.

Given the designation “LSMR” for “Landing Ship Medium – Rocket,” their size and cargo space enabled the ships to carry thousands of rockets at a time, and their shallow draft enabled them to sail up to the shore, giving them the ability to fire rockets further inland.

The first rocket fire support ships the US Navy operated, like the British-made Landing Craft Tank (Rocket) and the LSMR-188-class, though useful, had issues that hampered their effectiveness.

Although equipped with thousands of rockets, the launchers were welded in place facing forward, forcing the ship to point towards its target for all salvos — a difficult task in high winds, changing tides, or choppy seas. Additionally, it took hours to reload all of the launchers for a full salvo, and the crew had to be confined below deck during firing, as the exhaust from the rockets was toxic.

The solutions were the LSMR-401 and follow-on LSMR-501-classes; these designs modified from the LSMR-188 featured a better layout — the superstructure housing the bridge, for example, was moved aft and the 5-inch gun turret placed directly in front of it.

The armament was also further upgraded, with two 40mm and four 20mm anti-aircraft guns (which could be pointed horizontally to fire at land-based targets), four 4-inch mortars, and, depending on the layout, eight to ten Mark 102 double-barreled rocket launchers. The LSMR-501 class’s armament was slightly larger, with four 40mm and eight 20mm anti-aircraft guns.

The cornerstone of the ships’ armament, the Mark 102 rocket launcher, fired two 5.0-inch spin-stabilized rockets within one second, after which it was automatically reloaded within three seconds, enabling each launcher to fire about 30 rockets per minute — a blistering rate for rocket artillery systems.

Four types of rockets could be fired, with warheads ranging from 1.7 to 12 pounds and ranges of 1.4 to 5.6 miles. Depending on the makeup of the loadout, a ship could carry anywhere from 1,500 to 5,000 rockets.

The destructive potential of a single LSMR-401/501-class ship was large enough that the Navy boasted that it had as much firepower as five destroyers.

Future shore bombardment and LSMs

Despite its value and firepower, by 1970, White River was showing its age. It was ultimately deemed unfit for service that May and decommissioned and stricken from the Naval Vessel Register. The following November, the ship was sold for scrap.

In the decades since White River’s service, the Navy has largely replaced naval guns and rockets with cruise missiles and airstrikes from carriers as the service moved towards precision strikes, with less emphasis on volume of fire. In fact, with the decommissioning of the battleship USS Missouri in 1992, no gun on any ship in the US Navy is larger than 5 inches (a reference to the gun barrel’s diameter).

The role of shore bombardment and naval gun support more broadly was supposed to be handed over to 32 Zumwalt-class destroyers, each of which would be equipped with two 6-inch guns of the Advanced Gun System capable of firing Long-Range Land Attack Projectiles: rocket-assisted precision 155mm rounds that were envisioned to glide out to targets up to 80 miles away.

But development issues and cost overruns on the ships proved cost prohibitive, so much so that the planned order of 32 ships was reduced to just three. Consequently, the cost of the guided gliding shells jumped to as much as $800,000 per round.

In 2021, the Navy decided to replace the AGS guns on the existing Zumwalts with hypersonic missiles, effectively changing their shore bombardment role to that of an anti-ship surface combatant. In 2020, the USS Zumwalt successfully launched SM-2 anti-aircraft missiles from the newly installed MK 57 Vertical Launching System as well.

The fleet’s cruisers and destroyers are loaded with dozens of $2 million Tomahawk cruise missiles, but they too lack the volume of fire and reload capacity of a rocket artillery ship like the decommissioned White River.

Meanwhile, the Navy is also looking at rebuilding LSMs — a type of vessel that hasn’t been in the US Navy inventory for decades.

Originally proposed by the Marine Corps in 2022 and called the Light Amphibious Warship program, the Navy has since agreed on the need for smaller amphibious ships as a way to help lessen the reliance on the large Landing Helicopter Assault and Landing Platform Dock ships that make up the entirety of the amphibious ship force.

Now known as the Medium Landing Ship program, the Navy hopes to acquire 18 to 35 of the vessels. The ships would help the Navy and Marine Corps implement their Distributed Maritime Operations concept, which calls for US naval assets to disperse over large areas to reduce the risk of catastrophic losses from an enemy attack.

The Corps wants the new ships to be able to beach and unload Marines and their gear essential to setting up small expeditionary bases across the Pacific, but they’re also expected to be useful in noncombat operations or situations where there are no port facilities.

If the Navy ever decides to modify one of these future LSMs for deep fire support, it should look no further than the example set by the White River.

Benjamin Brimelow is a freelance journalist covering international military and defense issues. He holds a master’s degree in Global Affairs with a concentration in international security from the Fletcher School of Law and Diplomacy. His work has appeared in Business Insider and the Modern War Institute at West Point.