Robert would probably not carry laudanum in his bag as it was available without prescription in most pharmacies in the early 1900's. Opium itself has been known as a pain killer for centuries, and its highly addictive properties were often ignored when a powerful painkiller was required. It is important to remember that while physicians and surgeons knew that opium was effective as a painkiller, they did not know why it worked. The mechanisms of the brain and its receptors for opiates were simply not understood.
Unfortunately laudanum was also used by those who were not in pain as it was easily available in what were called Opium dens..but, I digress.