On September 8, 1565, with much pomp and circumstance and 600 voyagers cheering, Menéndez set foot on the shores of Florida. In honor of the saint whose feast day fell on the day he first sighted shore, Menéndez named the colonial settlement St. Augustine. Menéndez quickly and diligently carried out his king's instructions. With brilliant military maneuvering and good fortune, he removed the French garrison and proceeded to consolidate Spain's authority on the northeast coast of Florida. St. Augustine was to serve two purposes: as a military outpost, or PRESIDIO, for the defense of Florida, and a base for Catholic missionary settlements throughout the southeastern part of North America.

Maintaining St. Augustine as a permanent military colony, however, was a mighty task. Without the courage, perseverance, and tenacity of the early settlers, it is doubtful that the community would have survived.

English pirates and corsairs pillaged and burned the town on several occasions in the next century. Clashes between the Spaniards and the British became more frequent when the English colonies were established in the Carolinas, and later, in Georgia. The Spanish moved to strengthen their defenses, beginning in 1672 construction of a permanent stone fortress. The Castillo de San Marcos was brought to completion late in the century, just in time to meet an attack by British forces from the Carolinas in 1702. Unable to take the fort after a two-month siege, the British troops burned the town and retreated. In 1740, an even stronger attack was mounted by the Governor of the British colony of Georgia, General James Oglethorpe. He also failed to take the fort.