orce capable of undertaking offensive operations.
MacArthur decided to use the Joint Strategic and Operations Group (JSPOG) of his Far East Command (FECOM). The initial plan was met with skepticism by the other generals because Inchon's natural and artificial defenses were formidable. The approaches to Inchon were two restricted passages, Flying Fish and Eastern channels, which could be easily blocked by mines. The current of the channels was also dangerously quick—three to eight knots. Finally, the anchorage was small and the harbor surrounded by tall seawalls. Commander Arlie G. Capps noted, "We drew up a list of every natural and geographic handicap—and Inchon had 'em all."
These problems, along with the advancing North Korean army, forced MacArthur to abandon his first plan, Operation Bluehearts, which called for an Inchon landing in July 1950.
Despite these obstacles, in September, MacArthur issued a revised plan of assault on Inchon: Plan 100-B, codenamed Operation Chromite. A briefing led by Admiral James Doyle concluded "the best that I can say is that Inchon is not impossible." Officers at the briefing spent much of their time asking about alternative landing sites, such as Kunsan. MacArthur spent 45 minutes after the briefing explaining his reasons for choosing Inchon. He said that because it was so heavily defended, the enemy would not expect an attack there, that victory at Inchon would avoid a brutal winter campaign, and that, by invading a northern strong point, the UN forces could cut off North Korean lines of communication. Inchon was also chosen because of its proximity to Seoul. Admiral Forrest P. Sherman and General J. Lawton Collins returned to Washington, D.C., and had the invasion approved.
The landing at Inchon was not the first large-scale amphibious operation since World War II. That distinction belonged to the July 18, 1950, landing at Pohang. However, that operation was not made in enemy held territory and was unopposed.
Seven days before the main attack on Inchon, a joint Central Intelligence Agency–military intelligence reconnaissance, codenamed Trudy Jackson, placed a team of guerrillas in Inchon. The group, led by Navy Lieutenant Eugene Clark, landed at Yonghung-do, an island in the mouth of the harbor. From there, they relayed intelligence back to U.S. forces.
With the help of locals, the guerrillas gathered information about tides, mudflats, seawalls, and enemy fortifications. The mission's most important contribution was the restarting of a lighthouse on Palmi-do. When the North Koreans discovered that the allied agents had entered the peninsula, they sent an attack craft with 16 infantrymen. Eugene Clark mounted a machine gun on a sampan and sank the attack boat. In response, the North Koreans killed up to 50 civilians for helping Clark.
A series of drills and tests were conducted elsewhere on the coast of Korea, where conditions were similar to Inchon, before the actual invasion. These drills were used to perfect the timing and performance of the landing craft.
As the landing groups neared, cruisers and destroyers from several UN navies shelled Wolmi-do and checked for mines in Flying Fish Channel. The first Canadian forces entered the Korean War when HMCS Cayuga, HMCS Athabaskan, and HMCS Sioux bombarded the coast. The Fast Carrier Force flew fighter cover, interdiction, and ground attack missions. Destroyer Squadron Nine, headed by the USS Mansfield, sailed up Eastern Channel and into Inchon Harbor, where it fired upon enemy gun emplacements. The attacks tipped off the North Koreans that a landing might be imminent. The North Korean officer at Wolmi-do assured his superiors that he would throw the enemy back into the sea.
The flotilla of ships that landed during the battle was commanded by Arthur Dewey Struble, an expert in amphibious warfare. Struble had participated in amphibious operations during World War II, including the Battle of Leyte and the Battle of Normandy.
At 6:30 am on September 15, 1950, the lead elements of U.S. X Corps hit "Green Beach" on the northern side of Wolmi