So the concept of the operation took form. In early September, and again in the days preceding the landing, the three carrier units of Joint Task Force 7—Admiral Ewen’s fast carriers, Admiral Ruble’s escort carriers, and the British light carrier Triumph—would work over the west coast with their efforts gradually converging toward Inchon.
Prior to D-Day a destroyer and cruiser bombardment of Wŏlmi Do would be carried out.
On the early morning tide of 15 September a battalion landing team of the 5th Marines would assault Wŏlmi in order to secure that commanding position.
On the afternoon tide, at about 1700, the main attack into the city would be carried out by the 5th Marines’ remaining two battalions and by the 1st Marines. While the two Marine regiments moved rapidly to expand their holdings to Kimp'o airfield and the Han River line, the 7th Infantry Division (Reinforced) and corps troops would be landed administratively and would then operate as ordered by the corps commander.
Throughout the operation bombardment and fire support would be provided by cruisers and destroyers, and air cover, air strikes, and close support by carrier aviation.
So far as the air was concerned Joint Task Force 7 was self-sufficient: complications of coordination or control during the landing phase were fended off by the proviso that except at the request of Admiral Struble no FEAF aircraft would operate in the objective area subsequent to D minus 3, while for the later stages of the campaign X Corps was provided with its own Tactical Air Command, composed of Marine aircraft and commanded by a Marine brigadier general.
Such was the plan for the operation as worked out by the staffs of Seventh Fleet, the Amphibious Group, and the Marine Division. For Inchon, as for Pohang-dong, the planning was necessarily carried out in violation of all the rules and in record time.
By 2 September, when the Joint Task Force operation plan and the Amphibious Group’s operation order were issued, Marine planning was nearing completion,