Using Natural Resources
Zealous B. Tower was the civil engineer and soldier who was responsible for the construction of Fort Alcatraz. He needed to get things done as fast as possible, so he used anything nature provided. He and his crew used rocks to build the walls that would protect the island.
When the walls were all up, they could position their weaponry behind them. The weapons at Fort Alcatraz were at the north, south, and west sides of the walls. When it came to armed cannons, he and his crew set up a total of 111.