Fort Matanzas -- Ferry to Rattlesnake Island For more than 260 years, this fortress has guarded Matanzas Inlet, the backdoor entrance to St. Augustine. The river and inlet were given the name Matanzas, which is Spanish for slaughters, for the bloody confrontation that marked the beginning of 235 years of Spanish rule over Florida. In that confrontation in 1565, Spanish soldiers massacred 250 men of a French Huguenots ship's crew. The Spanish built a wooden watchtower in 1569 to guard the inlet, and fortified the garrison with a coquina fortress in 1740-1742.