On September 18, the British XII Corps attacked with the 66th and 67th Brigades of the 22nd Division and the Greek Serres Division. The Bulgarian first line of trenches was overrun and the Serres Division penetrated to the second line. The Bulgarians responded with heavy artillery fire and counter-attacks that recaptured the ground lost. Meanwhile, the British 66th Brigade's 7th Battalion, South Wales Borders lost heavily and failed in its attacks. Attacks by the 11th Welsh Regiment and 9th Border Regiment did not go well either. The British 67th Brigade's 12th Cheshire Regiment followed by the 9th South Lancashire Regiment and 8th Kings Shropshire Light Infantry (KSLI) advanced into Bulgarian artillery and machine-gun fire. the 67th Brigade lost 65% of its soldiers. At the end of the day the XII Corps was back at its starting point. On September 19, the XII Corps attacked again but because the XVI Corps attacks north of the lake had failed, the XII Corps would attack alone. The Greek Serres Division repeated the previous day's performance, taking some Bulgarian trenches, before being thrown back by heavy artillery, machine-gun fire and counter-attacks. The British attacked with the 77th Brigade, the weakened 65th Brigade, and later the 2nd French Zouaves. The 66th Brigades and 67th Brigades were fit only for defensive duties and did not participate. The 77th Brigade took some Bulgarian trenches but it was in an exposed position, being bombarded by artillery and eventually retreated before the Bulgarians counter-attacked. The brigade suffered about 50% casualties. The 65th Brigade's attack failed also, as did the French Zouaves.