Gregory Blaxland, William Lawson, and William Wentworth led an expedition in 1813 to find a way across the Blue Mountains west of Sydney, as the growing colony needed more land. They brought supplies for six weeks and cut their way through thick bushland. It was difficult work with dangers like slippery terrain. After finding grass and water, they saw good grazing lands beyond the mountains. Their successful crossing opened new areas for settlement and helped shape the colony's growth.