Promoted to major in 1934, Ichiki was assigned to the China Garrison Army as a battalion commander of the 1st Infantry Regiment in 1936. On 7 July 1937, the Japanese conducted a practice night attack around the bridge, firing blanks in the air. The Chinese, thinking an attack was underway, fired a few ineffectual artillery shells. A Japanese soldierfailed to show up for roll call the next morning, and Ichiki, his company commander, thought that the Chinese had captured him. He ordered an immediate attack on Wanping, precipitating the first real battle of the Second Sino-Japanese War. Recalled to Japan soon after the incident, Ichiki served as an instructor in specialized military equipment training schools from 1938 until 1940.
With the start of the Pacific War in 1941, Ichiki was promoted to colonel and was placed in command of the IJA 28th Infantry Regiment, from the 7th Division, which consisted of 3,000 troops, and was assigned to assault and occupy Midway island. The defeat of Japanese naval forces at the Battle of Midway in June 1942 forced a cancellation of the operation. In August 1942, Ichiki and his regiment were transferred to the IJA 17th Army in the southern front and were based at Truk in the Caroline Islands. After Allied forces landed on Guadalcanal in the Solomon Islands, as part of the Allied Guadalcanal campaign, Ichiki was assigned to take a portion of his regiment to recapture Henderson Airfield and drive the Allied forces off the island. On 19 August, six Japanese destroyers carried Ichiki and his 916 troops from Truk and landed them at Taivu Point on Guadalcanal. Ichiki had been ordered to wait on the beachhead for the remainder of his regiment, but finding the beach deserted and the island apparently lightly defended, Ichiki grossly underestimated the strength of the American forces, left a rear guard of 125 men, and advanced to make a nighttime frontal assault against the American positions. Unknown to Ichiki, the American Marines were aware of his landing and were entrenched in defensive positions. In the Battle of the Tenaru of 21 August 1942 Ichiki was defeated with extremely heavy losses. Recent Japanese scholarship disputes the claim that Ichiki was personally reckless/at fault, and say that the Imperial general staff put Ichiki in a suicidal position by ordering him to attack into prepared positions, outnumbered 15 to 1, with no air support, no naval support, no heavy guns, and poor intelligence that vastly underestimated American strength. The additional troops from his second group would not have changed this equation. However, the general staff needed someone to take the blame, and figured it was easy to blame Ichiki. There was also speculation that the General Staff preferred to send Ichiki to battle directly from the aborted Midway operation, figuring if the entire detachment went back to Japan the secret of the failure at Midway would leak. Accounts differ as to how Ichiki died. At least one account claims that Ichiki was killed in action during the heat of battle; others state that he committed ritual suicide due to the humiliation of his defeat in the battle. Despite the failure of his attack, Ichiki was promoted posthumously to major general.
