Robert Stobo was born in Glasgow, Scotland, in 1727. Following the deaths of his parents in the 1740s, Stobo moved to the Virginia colony to seek his fortune as a merchant. In Virginia, Stobo became a favorite of Governor Dinwiddie. As the conflicts of the French and Indian War escalated, Stobo joined the Virginia Regiment. He served as an engineer at Fort Necessity under the command of Lieutenant Colonel George Washington. After Fort Necessity fell to the French on July 3, 1754, Stobo was captured and became a prisoner of war at Fort Duquesne. The French occupied Fort Duquesne until November 1758 when they burned and abandoned the site; a year later, the British built Fort Pitt on the ruins.