The intensive shore bombardments required led to the deployment of the U.S. Navy’s Iowa-class battleships, and not for the last time their 16-inch guns fired in support of land operations. Cruisers, destroyers, and even small frigates played a part in neutralizing enemy shore defenses, and on some occasions even the carriers were able to fire their 5-inch batteries against shore targets. Techniques improved, with radar being used to assist in ranging and spotter aircraft reporting fall of shot. Here too was a skill that many pundits thought irrelevant to the age of missiles and nuclear weapons, but it was used in Vietnam, the Falklands, and the Gulf War.

In one respect, the U.S. Navy was caught napping: mine countermeasures. At Wonsan, a scratch collection of North Korean junks and fishing vessels had laid sufficient Soviet mines to dislocate the timetable for the amphibious landings. But the most alarming news was the discovery that even the best minesweepers the U.S. Navy had were unable to neutralize the Soviet magnetic mines laid in shallow waters.

In one respect, the U.S. Navy was caught napping: mine countermeasures. At Wonsan, a scratch collection of North Korean junks and fishing vessels had laid sufficient Soviet mines to dislocate the timetable for the amphibious landings. But the most alarming news was the discovery that even the best minesweepers the U.S. Navy had were unable to neutralize the Soviet magnetic mines laid in shallow waters. For the D-Day landings in 1944, the U.S. Navy and the Royal Navy had provided wooden hulled minesweepers to deal with the latest German magnetic and acoustic mines. But these craft proved unable to make any headway against the mines off the invasion beaches of Wonsan. The reason was simple; Soviet scientists had designed an actuator sufficiently sensitive to pick up the residual magnetism in such items as the engine blocks of the minesweepers’ diesels.

Space is insufficient to allow a full account of how the U.S. Navy and its NATO allies met the Soviet mine threat, but it was countered effectively for decades. Although initially seen as a tactical threat to invasion forces, the problem was very relevant to U.S. strategy in Europe. To meet any Soviet land offensive against Western Europe the U.S. Navy and NATO would have to guarantee the safe arrival of resupply convoys in European ports. If those ports were blocked for any length of time by air- or submarine-laid mines, NATO could lose the war and Western Europe would fall under Soviet control. The U.S. Navy began a massive construction program of minesweepers with very low magnetic “signatures,” while the British led a similar West European program partially funded under the Mutual Defense Assistance Program (MDAP). Advances in underwater detection led to a new concept of “hunting” for mines rather than sweeping them, using a high-frequency sonar to identify individual mines. A clearance diver would then demolish the mine with an explosive charge.

Electronic warfare (EW) was in its infancy in World War II, but its use expanded greatly in Korea. EW took two main forms, electronic countermeasures (ECM) or active jamming of hostile radars, and electronic support measures (ESM), passive analysis of radar and radio signals. At its simplest ESM was no more than a radar warning receiver (RWR) to give timely warning of an impending attack, while at the “top end” it could be used to eavesdrop on enemy communications. EW was shrouded in secrecy during the Korean War, but it made great strides, putting both the Air Force and the Navy in an excellent position to exploit the electromagnetic spectrum when the Vietnam War started.

The Korean War marked a transition from the ships, weapons, and ideas of World War II to the much more advanced systems available at the height of the Vietnam War and afterwards. Without Korea, the U.S. Navy and others of the Western Alliance might have remained locked into World War II thinking.

The Korean War marked a transition from the ships, weapons, and ideas of World War II to the much more advanced systems available at the height of the Vietnam War and afterwards. Without Korea, the U.S. Navy and others of the Western Alliance might have remained locked into World War II thinking. At this distance it is hard to recall how much military strategy was dominated by “The Bomb.” Despite the conflicting evidence of the Bikini nuclear tests, it was widely assumed that navies would have no role to play in a nuclear conflict. The extreme exponents of nuclear deterrence found a useful ally in air forces, notably the Strategic Air Command (SAC) set up by the newly independent U.S. Air Force, and its faithful disciples in the Royal Air Force on the other side of the Atlantic. They succeeded in convincing their respective governments that World War III would start with only four minutes’ warning, followed by a nuclear exchange that would cause huge civilian casualties and damage to cities.

Korea showed that a confrontation with communism need not result in nuclear war. As we now know, President Harry S Truman had no intention of launching nuclear strikes against China, which is why he had to rein in Gen. Douglas MacArthur when he tried to dictate policy. Although the “umbrella” of nuclear deterrence was never abandoned, Korea showed that “limited” war for limited objectives was possible, and in that sense provided a foretaste of Vietnam, a conflict in which the Soviets and Chinese also wanted to support Ho Chi Minh but were inhibited in the extent of that help. Part of that inhibition in both conflicts was also recognition of the fact that the U.S. Navy controlled the oceans, making any direct intervention by the Soviet Navy impossible. Conversely the U.S. Navy had unlimited access to the sinews of war, which arrived without interference or delay.

The U.S. Navy had such a large number of modern warships that it had no need to start new construction. But lessons were incorporated into the new designs emerging, notably the super-carriers and the modernized Essex-class wartime carriers. The virtual absence of effective hostile air attacks on ships by the North Koreans and Chinese had no effect on the drive to create successful surface to air missiles, not least because of the fear of kamikaze attacks. The first anti-aircraft missile cruisers, the USS Boston and the USS Canberra, completed their conversions to launch Terrier missiles in 1955-1956, followed by six smaller Cleveland class in 1958-1960.

The first anti-aircraft missile cruisers, the USS Boston and the USS Canberra, completed their conversions to launch Terrier missiles in 1955-1956, followed by six smaller Cleveland class in 1958-1960.

The destroyer force was facing block obsolescence. The older ships had seen arduous war service, and even the most modern were mostly optimized for torpedo attack on an enemy surface fleet. To extend their useful lives a massive Fleet Rehabilitation and Modernization (FRAM) program was put in hand to improve air defense, anti-submarine warfare (ASW) and electronics, and to refurbish hulls for at least eight more years of service. In fact, they served for many years longer than expected.

Submarines played only a small part in hostilities, mainly landing and extracting reconnaissance parties. There were no targets worth a torpedo, and trying to sink junks in shallow, restricted, and possibly mined waters risked losing the submarine. Conversely, the lack of a North Korean submarine force allowed U.N. ships to operate with impunity close inshore, navigation being the main consideration. Any sign of intervention by Soviet submarines would, of course, have been countered by U.S. submarines, but there is no proof that such a move was ever contemplated.

Korea was in every sense a limited war. Bombardments from the sea or from the air could not be indiscriminate due to the danger to the South Korean civilian population. To the north lay Manchuria, and any attempt to operate across the Chinese border could and did provoke Chinese retaliation.

Korea was in every sense a limited war. Bombardments from the sea or from the air could not be indiscriminate due to the danger to the South Korean civilian population. To the north lay Manchuria, and any attempt to operate across the Chinese border could and did provoke Chinese retaliation. No “colonial” war had ever been fought with such constraints, and the victors in  World War II seemed at times baffled by them.

This article was first published in The Forgotten War: 60th Anniversary of the Korean War.