The service of medical practitioners in the early Australian colonies was inextricably bound up with a heavily militarized culture. This paper explores the relationships between those medical practitioners, legal punishment, and the British Empire in the first half of the nineteenth century. The service of medical practitioners in the Australian colonies, coming as it did so close on the heels of two generations of war, gives us an important insight into the effects of the Napoleonic wars both upon the practice of medicine in the service of the British State, and also the State’s attitude to the use of medical expertise. In the military spaces of transport and colony, the medical officer became an important lynchpin in the discipline and control exercised over convict bodies. Military medical expertise was useful to the State in understanding the best ways to discomfort and hurt convicts, without quite killing them. This expertise was further cultivated by the State in the ongoing design of the medical role in the colonies that came to hark forward to the prison officer of the later nineteenth century whose position, balanced precariously between punishment and care, has been of such interest to penologists and medical historians.