After a funeral conducted by the Chairman of the Joint Chiefs of Staff, he was buried at the Daejeon National Cemetery on 17 January 2002.

After graduating from the JFAS in 1943, he, by then an artillery captain,[2] served in the Japanese Army in China and Vietnam until the end of World War II (14 August 1945).

In October 1945, Lee Hyung-geun, age twenty-four, returned to Korea, where he worked briefly as an English teacher at the Daejeon Middle School.

[11] On 28 September, Lee at age twenty-five was appointed as the acting Commander-in-Chief of the Guard, the first Korean to hold this position, and served in the role until December.

After ceasing command of the Guard near the end of 1946, it is unclear what occupied Lee Hyung-geun during 1947, except becoming the father of his first child, a boy on 21 July.

However, in February 1948 Lee became the Chief of Staff for the Department of Internal Security, the forerunner of the Ministry of National Defense, created the same day as South Korea (15 August 1948).

After an assignment as the first military attaché at the ROK Embassy in Washington, DC,[11] Lee returned to Korea, where on 20 June 1949, as Brigadier General, he became the first commander of the newly established 8th Army Division.

On 2 December 1952, U.S. President-elect, Dwight D. Eisenhower, went to Korea to assess the war situation and to visit troops, commanders, and Korean leaders.

[2][8] A location known as “Hill 351” came into play at least once toward the end of the war and involved Lee Hyung-geun as Commander of ROK Army I Corps.

[2] Because the contents of all these accounts tend to suggest two different events, it is likely that there were two Battles of Hill 351 – one in 1952, the other in 1953 – with the second more important than the first, because it extended the northeast part of the Armistice line well north of the 38th Parallel.

Although the war did not officially end then or since, the agreement established a division of the Korean Peninsula roughly along the 38th Parallel, around which most of the battles had occurred inconclusively during the two previous years.

In this capacity and at the invitation of Free China, General Lee visited Taiwan in February 1957, where he inspected troops and military facilities.

The next year he was appointed as the fourth Ambassador Extraordinary and Plenipotentiary to the United Kingdom, serving 16 August 1962 – 11 December 1967.

[29][30] While in this role, he served concurrently as the ROK Ambassador to Denmark, Norway, Sweden, Iceland, Malta, Sierra Leone, Gambia, and Malawi.

[11] Lee Hyung-geun returned to South Korea late in 1967 and continued to serve the ROK as a private citizen for many years.