With the outbreak of the French and Indian War in 1754 Heard left school in search of honor and adventure in the army. Along with some of his brothers, Heard enlisted in the Virginia colonial regiment under the command of Colonel (at the time) George Washington. This experience gave Heard a thorough understanding of warfare in the frontier which he would go on to use later in his life. During the war, Heard fought valiantly and was promoted by Washington to the rank of captain. Heard served with Washington at the Battle of Jumonville Glen, Battle of Fort Necessity, Braddock Expedition and the Battle of the Monongahela. Heard also served under Washington on the Virginia frontier (in what is today the state of West Virginia from August of 1755 until early 1757 as part of the Virginia regiments war against Native American forces in that region. Heard also served directly under Washington during the Forbes expedition. This military collaboration led to a lifetime friendship between George Washington and Stephen Heard. Heard would even go on to name his son George Washington Heard. Heard was one of very few Virginians to take part in the Battle of the Plains of Abraham and the only (known) Virginian to take part in the Battle of Signal Hill.