In July 1865, almost 1,000 New Brunswick militiamen assembled in Fredericton for a twenty-four day Camp of Instruction. This was the first time peacetime militia training on this scale was ever attempted in British North America. At the time, and since, the camp was praised as a notable achievement. New Brunswick’s lieutenant-governor and provincial commander-in-chief, Arthur Hamilton Gordon, wrote: “The entire success of this experiment is admitted with an unanimity which is remarkable, because rare in this Province.” Although the uniqueness of the camp has been the subject of some interest, it has never been subjected to more in-depth analysis. This article moves beyond generalizations to examine the purpose of the camp and what actually transpired. The Camp of Instruction tells us a great deal about the nature and character of New Brunswick’s militia on the eve of Confederation, and its outcome helps to explain why the province moved towards political union as an answer to the inadequate state of its defences.