This led to a number of battles in the steep mountains of the Finnisterres. In October, battles took place at Palliser's Hill, and then later at Johns' Knoll where the Australians first managed to capture the knoll and then held it against a determined Japanese counterattack. In November, the 25th Brigade relieved the 21st as the offensive was maintained, and later in December and into January heavy fighting took place around Shaggy Ridge, a long spur dotted by several rocky outcrops. The Japanese had established numerous strong posts and positions along the ridge, blocking the Australian advance towards the coast, where they were aiming to secure Bogadjim and Madang. The initial attacks on Shaggy Ridge began on 27 December with a heavy artillery and air preparation of the Japanese positions around The Pimple, a steep rocky outcrop, which commanded the southern half of the position and had prevented the Australians advancing over the previous two months. These preparatory fires were followed by an assault up the steep slopes of The Pimple by the 2/16th Infantry Battalion, which employed ladders made out of bamboo to help scale the face of the slope. Held up overnight by a Japanese pillbox, the 2/16th resorted to explosives to destroy it.