[5] The Neutral Strip was created after the 1803 Louisiana Purchase, from which arose a disagreement about the location of the border between the American and Spanish territories.

In order to avoid a war, the two countries agreed that the land in contention would remain neutral and free of armed forces from either side.

The Neutral Strip remained devoid of government and law enforcement until the Adams–Onís Treaty of 1819 finally set the border at the Sabine River.

His forces, known as the Army of Observation, remained in the fort and monitored the Texas territory as it passed from Spanish to Mexican control, and finally broke away as an independent republic.

The site was acquired by the Louisiana Office of State Parks in 1956, and in 1961, the fort was designated a National Historic Landmark.