He became the co-leader, along with Hamilton Hume, from the infamous expedition of Eastern Australia. When his dad was captured and imprisoned with the French, youthful William slipped out of college to supply for his family members. He and Hume noticed each other much less companions, but as competitors, which nearly doomed their expedition. His dad commanded a dispatch that exchanged in the Mediterranean. During his expedition he discovered a river, afterwards called the Murray River, by Australian explorer Charles Sturt.