|(clockwise from upper left: Ft. Pickens; Ft. Pike/Macomb; Ft. McRee; Advanced Redoubt of Ft. Barrancas; Ft. Point; Ft. Jefferson)|
The Third System commenced in the wake of the War of 1812. The U.S. had learned a painful lesson about protecting its harbors and rivers from enemy ships. Since we didn't like the British anymore, we got French experts to help build strong and modern brick and stone defenses that were unbeatable at the time. The first was little pie-shaped Fort Pike (commenced 1819, completed 1827) guarding the Rigolets Pass into Lake Pontchartrain. This was the first of five forts controlling access to New Orleans and the Mississippi River.
Fort Pickens was the first of four forts guarding Pensacola's harbor and navy yard. Building commenced in 1829 and wrapped up in 1834. Almost immediately thereafter, engineers got to work on the smaller Fort McRee (1834 to 1839), putting it across the channel from Pickens to develop a withering crossfire on enemy ships.
As soon as McRee was done, Fort Barrancas was commenced in 1839 and finished in 1847; a smaller supporting structure, the Advanced Redoubt (1845-1870), was built a few hundred yards to the north. Together they controlled the landward approaches to the navy yard peninsula.
Forts Barrancas and its Redoubt show the evolution of American fortification away from the bulkier and massive (and more elaborate) Fort Pickens toward simpler construction. Curtain walls, casemate arches and bastions were pared down to essentials. Solid brick walls gave way to inner and outer brick facings with concrete poured between them for strength.
Fort Jefferson (1846-1874) exemplifies this leaner approach to construction. It covers a larger area, is taller, has longer walls, and was designed for more guns than Fort Pickens, but uses 75% as many bricks (16 million vs. 21.5 million).
Fort Point (1853-1861) is comparable in size to Forts Pike and McRee but could mount more guns (126, compared to Pike's 43 and McRee's 110). This was the only such fort built on the West Coast.