Final answer:
The first British fort constructed in Georgia was Fort King George, established in 1721, predating the construction of Fort Frederica in 1736.
Step-by-step explanation:
The name of the first British fort constructed in Georgia was Fort King George. Built in 1721 at the mouth of the Altamaha River, it marked a British presence deep within the contested frontier, amidst Spanish-claimed territories. This fort was critical in securing the region and offering a warning system against potential Spanish activities. Despite struggles including starvation and disease, which led to the fort being nearly abandoned, Fort King George stands as the earliest fort in the territory that would become Georgia. Most famously, Fort Frederica became a significant stronghold after its construction in 1736 on St. Simon's Island. However, it was not the first fort built in the Georgia area by the British.