Early in the new year, the 15th and 18th Brigades relieved the 21st and 25th Brigades around Shaggy Ridge, and planning for a new offensive began. The major Australian attack on Shaggy Ridge – codenamed Operation Cutthroat – was launched by the 18th Brigade on 19–20 January. The 2/4th Field Regiment, which established its guns around the Lake area to the west of the Mosia River, and south of Guy's Post, while stores were brought up to that position by jeep. The brigade's three battalions were to converge on the Kankiryo Saddle from three different directions: the 2/12th Infantry Battalion was to advance from Canning's Saddle, east of Shaggy Ridge, and attack two well-defended knolls on the northern end of Shaggy Ridge, known as Prothero I and II; the 2/9th Infantry Battalion would attack northwards along Shaggy Ridge itself, to take McCaughey's Knoll, by way of Green Sniper's Pimple; and the 2/10th Infantry Battalion would advance along Faria Ridge, which lay to the east of Shaggy Ridge and joined it at Kankiryo Saddle.