Immediately following the conclusion World War II, Allied powers studied captured and surrendered German technology, specifically the V-2 rocket— the world's first large-scale liquid-fuel rocket— for use in their own militaries . The United States Navy investigated the possibility of launching these vehicles from the decks of aircraft carriers, an ability that would vastly increase their striking range. Thus began Operation Sandy, a project aimed at testing the feasibility of launching a V-2 rocket from the sea.
The Sandy rocket on the deck of the USS Midway (midwaysailor.com)
The USS Midway was selected as the "launch pad" for Operation Sandy not only because its deck was spacious enough to accommodate the special launching apparatus needed for the rocket, but also because it was made of steel— engine ignition or an unfortunate rapid unscheduled disassembly would ignite the decks of Essex-class carriers, which were made of teak wood. According to the Hampton Roads Naval Museum's website, an official Navy report states Midway was selected for "its elevator capacity, its fire fighting facilities, and because of its steadiness at sea" [a]. The ship's sailors were trained on operating the missile by the Army ordnance unit at the White Sands Proving Ground in New Mexico, the then-future launch site of modified V-2 rockets called Bumpers . Preliminary testing of Operation Sandy's launch apparatus was conducted at White Sands, as well as the construction of two rockets, which were then shipped across the country to the Norfolk Naval Shipyard in Virginia. The launch vehicles and spare parts were placed atop the deck of Midway before the ship was escorted into the Atlantic Ocean by four destroyers.
Deliverance of "Sandy" to the USS Midway (Hampton Roads Naval Museum)
Admiral Forrest Sherman, the Deputy Chief of Naval Operations, and Admiral William Blandy, the Commander in Chief of the U.S. Atlantic Fleet, toured the "launch site". The launch occurred on September 6, 1947, 250 miles (402.34 kilometers) southeast of Bermuda— all guests watched the event from the island for safety reasons. After a few seconds of flight following ignition, the rocket tipped to a 45 degree angle but corrected itself. It cruised to an altitude of between 12,000 and 15,000 feet (2.27 and 2.84 miles or 3.66 and 4.57 kilometers) before breaking apart. Despite the rocket's premature destruction, Operation Sandy was deemed successful. It was the hope of the U.S. Navy to implement regular firings of large rockets (non-sounding rockets) into its carriers' fighting strategies. Operation Pushover was the 1949 follow-up to Sandy during which a V-2 was literally "pushed" over onto a replica section of the carrier's flight deck to investigate the consequences of a fully-fueled vehicle toppling over. Although this capability was not adopted, Operation Sandy would not be the only time a rocket launched at sea.
Ignition and liftoff from Midway courtesy of a U.S. Navy documentary (Hampton Roads Naval Museum)
Less than two years after the Sandy launch, the USS Norton Sound launched the fourth Viking sounding rocket on May 10, 1950 . Viking was, at the time, the Navy's largest upper atmosphere research rocket with a whopping height of 45 feet (13.71 meters) and a diameter of 2.5 feet (0.76 meters). It was also the predecessor to the infamous Vanguard rocket. The Norton Sound's Viking was launched in the Pacific Ocean south of Hawaii between Jarvis Island and Christmas Island and reached an altitude of roughly 106.4 miles (171.23 kilometers). According to Time, it also carried a "1,000-pound (453.59-kilogram) instrument suite to study high-altitude cosmic rays" [b]. This launch was called Project REACH. Norton Sound also participated in the Navy's contribution to the International Geophysical Year in the late 1950s and Project Argus, a series of low-yield high-altitude nuclear weapons tests .
The Italian San Marco 2 satellite was the first payload carried into space by a vehicle launching from a sea-based platform . An American Scout B rocket launched from what became the San Marco Platform off the coast of Kenya on April 26, 1967. Previously, the former oil platform supported launches of small sounding rockets but is now inactive.
Scout rocket onboard the San Marco Platform (Public Domain)
The most ambitious of all sea-launched rockets over the past 75 years is by far the mighty Sea Dragon, a 1962 concept of a two-stage orbital super heavy-lift vehicle. It is the largest launch vehicle ever conceived, with a height of a 490 feet (150 meters) and diameter of 75 feet (23 meters), and the second largest in terms of low Earth orbit payload capacity. Unlike the other launch vehicles discussed in this post, Sea Dragon's launch pad would not have been a sea-based platform but rather the ocean itself: The rocket would be assembled on land and horizontally towed to a designated spot in the water before being fueled. A ballast would serve as a vertical stabilizer prior to liftoff as well as a protective cap for the vehicle's single massive engine. The ocean would suppress the sound of the engine and eliminate the need for constructing a new launch complex and support structures for such a vehicle. More information about Sea Dragon can be found in my Sea Dragon post.
Depiction of Sea Dragon being configured for launch (wikipedia)
75 years later, Operation Sandy is little more than an obscure footnote in the history of rocketry and space exploration. Today, though, it is much more common for launch vehicles to land on barges at sea rather than launch from them (a feat I've personally never come across in historic concepts). Perhaps as space becomes more privatized, companies will revitalize the bygone technologies discussed in this post and sea-based launches will become a thing of the present, not a thing of the past.
Author's note: Thanks for reading and be sure to like and share this post!
 One example is the British Operation Backfire, which performed test flights of the vehicle over the North Sea.
 The Bumper rocket was a combination of the V-2 and the Army's WAC (without any control) Corporal upper stage. Bumper 8 was the first rocket launched from Cape Canaveral in Florida.
 Viking was also test flown at White Sands.
 The Navy's primary contribution was the Vanguard satellite and launch vehicle program.
 San Marco 1 was launched from Wallops Flight Facility in Virginia onboard a Scout X-4.
Darling, David. "San Marco Launch Platform and Satellites." https://www.daviddarling.info/encyclopedia/S/San_Marco_launch.html
"Operation Sandy A4/V-2 ship launch." http://weebau.com/rock_us/a4_sandy.php
[a] Palmer, Elijah. "USS Midway Launches a V-2: Operation Sandy." Hampton Roads Naval Museum, June 22, 2016, https://hamptonroadsnavalmuseum.blogspot.com/2016/06/uss-midway-launches-v-2-operation-sandy.html [a]
[b] "Science: Rocket Away." TIME, May 22, 1950. https://content.time.com/time/subscriber/article/0,33009,812510,00.html