Working closely with the 5th Infantry Division, it moved through northern France up to the Moselle region, where it was involved in the Battle for Metz through September, October and November.

After securing the Allied flanks and mopping up the Bulge, it refitted for two months before fighting south along the Siegfried Line and crossing the Rhine in March.

[2] After a series of training posts in Louisiana, Virginia and New Jersey,[3] the battalion was shipped out of New York aboard the USS Fairisle in October 1943, to be stationed in Northern Ireland.

[11] In early September, the 5th Division probed through Verdun towards Metz;[12] Company C of the 818th supported an unsuccessful attempt to bridge the Moselle at Dornot, but was held in reserve and did not see significant action before the bridgehead was withdrawn.

[13] A second attack, at Arnaville south of the city on 10 September, was supported by B Company;[14] the M10s were held back on the western bank of the river, placed on a bluff with good views over the bridgehead to the east.

[19] The 5th Division and elements of the 818th began the final attack on Metz on 10 November, clearing the city by the end of the month and moving east across the German border.

[22] For the next ten days, the battalion pressed north, with the companies split up among the divisional infantry regiments, until they came to a standstill in Luxembourg at the end of the month.

[24] The M36 was a development of the M10; it used the same hull and engine, but mounted a larger turret housing a substantially more powerful 90mm gun; in some situations, it was capable of destroying an enemy tank at more than two and a half miles (around 4 km).

As had become routine by this point, the companies of the 818th operated separately, in close contact with the division's infantry regiments; they broke through the line on 18 March, and pressed eastwards towards the Rhine.

[28] Following VE-Day on 7 May, the battalion was tasked with guarding German prisoners, slowly transitioning to more general occupation duties before being withdrawn to Germany in late July to prepare for demobilization.