He joined the local militia (likely the Connecticut Line), quickly rising to the rank of Lieutenant Colonel due to his leadership skills.

At the outbreak of fighting in the American Revolutionary War (1775–1783), Hull joined a local militia and was quickly promoted to captain, then through the ranks to lieutenant colonel in the Continental Army.

He fought in the following battles of the Revolutionary War: White Plains, Trenton, Princeton, Stillwater, Saratoga, Fort Stanwix, Monmouth, and Stony Point.

Hull was largely responsible for making known and publicizing the famous last words attributed to Hale, "I only regret that I have but one life to give for my country.

[7] On March 22, 1805, President Thomas Jefferson appointed Hull as Governor of the recently created Michigan Territory and as its Indian Agent.

He negotiated the Treaty of Detroit in 1807 with the Odawa, Chippewa, Wyandot, and Potawatomi tribes, which ceded most of Southeast Michigan and northwestern Ohio to the United States, to the mouth of the Maumee River where Toledo developed.

[10] Hull was in Washington, D.C., when 6th U.S. Secretary of War William Eustis (1753–1825, served 1809–1813), informed him that President James Madison wished to appoint him a Brigadier General in command of the newly organized Army of the Northwest.

Hull at this point, was nearly 60 years old and had little interest in a new military command, so Colonel Jacob Kingsbury was selected to lead the force instead.

In the meantime, while camped at the Maumee Rapids, taking advantage of the waterway, he sent the schooner Cuyahoga Packet ahead of the army to Detroit with a number of invalids, supplies, and official documents; but the British commander at Fort Amherstburg had received the declaration of war two days earlier, and he captured the ship as it sailed past.

Hull began an invasion of Canada on July 12, 1812, crossing the Detroit River east of Sandwich (the area around Windsor, Ontario).

[16] He issued a proclamation to the "inhabitants of Canada" indicating that he wanted to free them from the "tyranny" of Great Britain and to give them the liberty, security, and wealth which his own country was experiencing—unless they preferred "war, slavery and destruction".

A group of 600 troops led by Lieutenant Colonel James Miller remained in Canada, attempting to supply the American position in the Sandwich area, with little success.

It is far from my intention to join in a war of extermination, but you must be aware, that the numerous body of Indians who have attached themselves to my troops, will be beyond control the moment the contest commences.

[27] That June, the Marquis de Lafayette visited him and declared, "We both have suffered contumely and reproach; but our characters are vindicated; let us forgive our enemies and die in Christian love and peace with all mankind.