The 'Battle of Oktwin' was fought between Japanese and Chinese forces as the second battle of the 'Battle of Yunnan-Burma Road' within the Burma campaign (20/23 March 1942).

On 20 March, as Lieutenant General Shojiro Iida’s Japanese 15^th Army moved to the north through Burma, its 143^rd Regiment and elements of the 55^th Cavalry Regiment, detached for the separate task of capturing Tavoy and Mergui, of Lieutenant General Hiroshi Takeuchi’s 55^th Division attacked the positions of the Chinese 5^th Army Cavalry Regiment to the north of the Kan river, driving the Chinese forces back with heavy losses. Most of the Chinese were then withdrawn to an area to the north of Toungoo, leaving only single companies of cavalry and infantry to delay the advancing Japanese. Meanwhile, Major General Dai An-lan, commander of the Chinese 200^th Division, moved his formations into the fortifications which had been constructed at Oktwin and around Toungoo. These defences had been built of timber, which was in abundant supply, and all the positions had been carefully concealed. On 21 March, Japanese forces brushed aside the delaying forces and reached the 200^th Division’s outposts at Oktwin.

The 55^th Division's 112^nd Regiment attacked the 200^th Division’s positions at first light on 22 March but made little headway. The Japanese forces attacking the positions occupied by the 1/600^th Regiment were one infantry battalion and several pieces of artillery. The Japanese then despatched a cavalry forces round the Chinese left flank, and the position was stabilised only after reservee forces of the 1/598^th Regiment had been committed in counterattacks.

The Japanese were now more careful after their vanguard had been ambushed, and used their artillery and machine guns to fire at suspected positions before committing their infantry. Light machine guns were positioned up among the trees and caused many Chinese casualties. Eventually the Chinese set up their heavy machine guns to deal with this menace.

On 23 March, the Japanese attacked once again on the left flank with strong artillery and air support. The battle continued until 16.00 without much success for the attackers, who then tried another flanking move with a company of infantry and scores of cavalry troopers around the right-hand side of the Chinese positions. The Chinese held their ground until the fall of night and only then fell back to their main defensive line at Toungoo on 24 March.