On 3 September, during the Battle of Guillemont (3–6 September), 12th Battalion lost 328 men in an attack that succeeded in occupying the German second line from Wedge Wood to the southeastern edge of Guillemont. After the village was captured the battalion pushed on to Leuze Wood, nearly east of Guillemont, completing an advance of by 95th Brigade during the battle. The battalion was in action again during the Battle of Morval (25–28 September) when, along with 2nd Battalion King's Own Scottish Borderers, it captured the southern half of Morval.