Florida's Governor Montiano establishes a fortified town for escaped enslaved Africans from the South Carolina Colony, granting them citizenship and freedom in return for their serving in the militia.

Established on March 15, 1738, Fort Gracia Real de Santa Teresa de Mose becomes the first free black settlement legally sanctioned in North America and a haven for escaped slaves from all the British colonies to the north.

Here, the freedmen will cultivate the ground and learn the Catholic religion.

Manuel de Montiano, born in the city of Bilbao, in the Basque Country in northern Spain, is the older brother of Agustín de Montiano, a dramatist and noted historian who had founded the Real Academia de la Historia in 1735 and become its first director.

While still a young man, Montiano had joined the Royal Spanish Army, and served for three years in the Aragon Regiment.

From there he was transferred to Darién in Panama.

He was by 1719 a captain of grenadiers and was sent to Oran, in what is now Algeria, where he had fought in the defense of the city against the Arabs.

Montiano on April 29, 1737, had been named Governor of La Florida.

Shortly after his taking possession, he had written to the Governor of Cuba notifying him of a forthcoming British invasion, and requesting supplies to ward off the danger.

Fort Mose, located two miles north of St. Augustine, had been established in 1738 by escaped black slaves from the British colony of Georgia who had been granted their freedom by Spain in return for Catholic conversion and four years of service to Spain.

The new fort, which is the first settlement of free blacks in North America, consists of a church, a fence with some towers, and some twenty houses inhabited by a hundred people.

The men have been made Spanish militia by Governor Manuel de Montiano and put under the command of Captain Francisco Menendez, a free black with military experience.

Fort Mose's militia had soon become a well-trained unit, as Saint Augustine has had a militia corps of free blacks and mulattoes since 1683.

The fort serves as a maroon colony and as Spanish Florida's front-line of defense against English attacks from the north.

Spain also aims to destabilize the plantation economy of the British colonies to the north by creating a free black community that will serve as a beacon for slaves seeking escape and refuge.

At the outbreak of the War of Jenkins’ Ear in 1739, General James Oglethorpe, governor of Georgia, encouraged by some successful raids in the frontier, had decided to raise a significant expedition to capture St. Augustine from the Spanish.

Regular troops from South Carolina and Georgia, militia volunteers, about six hundred Creek and Uchise allies and about eight hundred black slaves as auxiliaries, make up the expedition, which is supported by sea by seven ships of the British Royal Navy.

Montiano, who only disposes of about six hundred men including reinforcements recently arrived from Cuba, is forced to resist entrenched, although on several occasions he attacks the British lines by surprise.

Approaching St. Augustine, a British party under Colonel John Palmer composed of one hundred and seventy men belonging to the Georgian colonial militia, the Scottish Highlander 42nd Regiment of Foot and the auxiliary native allies, rapidly occupies Fort Mose, strategically situated on a vital travel route.

The fort had been previously abandoned by orders of Manuel de Montiano due the assassination of some of its inhabitants by native allies of Great Britain.

Montiano, who knows the strategic importance of Fort Mose, decides to recover it.

At dawn on June 15, Captain Antonio Salgado commands Spanish regulars, free blacks led by Francisco Menendez and native auxiliaries in a surprise attack on Mose.

The attack is initiated two hours before the British soldiers awake so that they cannot prepare their arms for defense.

About seventy of them are killed in bloody hand to hand combat with swords, muskets and club work.

The Spanish victory at Fort Mose demoralizes the badly divided British forces and supposes a significant factor in Oglethorpe’s withdrawal to Savannah.

St. Augustine is in late June  relieved from Havana and the Royal Navy’s warships abandon the land forces.

Governor Montiano commends the free black militia for their bravery, and although Fort Mose had been destroyed during the siege, their inhabitants are installed in St. Augustine for the next decade as free and equal Spanish citizens.

Matanzas Inlet, the southern mouth of the Matanzas River, can be used as a rear entrance to the city of St. Augustine.

Such an approach avoids St. Augustine's primary defense system centered at Castillo de San Marcos.

Governor James Oglethorpe of Georgia in 1740 uses the inlet to blockade St. Augustine and launch a thirty-nine day siege, which St. Augustine endures, but the Spanish realize the need to protect the inlet.

Construction begins in 1740 under Governor Manuel de Montiano.

Convicts, slaves, and troops from Cuba are used as construction labor.

The fort is sited on Rattlesnake Island and has a commanding position over Matanzas Inlet.

Fort Matanzas is constructed of coquina, a common shellstone building material in the area.

It is fifty feet (fifteen meters) long on each side with a thirty-foot (nine point one meter) tower.

The marshy terrain is stabilized by a foundation of pine pilings.

The standard staff for the Fort is one officer in charge, four infantrymen, and two gunners, though more troops can be stationed if necessary.

All soldiers at Fort Matanzas serve on rotation from their regular duty in St. Augustine.

Five cannons are placed at the Fort—four six pounders and one eighteen pounder.

All guns can reach the inlet, which at this time is less than a half mile away.

As the Fort is nearing completion in 1742,  the British under Oglethorpe approach the inlet with twelve ships.

Cannon fire drives off the scouting boats and the warships leave without engaging the Fort.

This brief encounter is the only time Fort Matanzas will fire on an enemy.