Construction designs for both East and West Martellos were identical. Central citadels, built in the shape of a square, had sides measuring 56’ across at the base and a height of 36’. Outer walls were 8’ thick on the seaward side but only 5’ thick on the landward side.
Structural plans for the citadels called for the lower floor to include a mess room, kitchen, closets, privies, a magazine, and supply rooms. The second floor was intended to incorporate sleeping accommodations for up to 60 soldiers and three private rooms for officers.
Based on techniques used during the Roman Empire, a complex design of arched ceiling joints was employed by 19th century engineers, thus allowing the citadel’s roof to hold heavy artillery. While it is uncertain the exact type of weaponry intended for installation at the Forts, it is safe to reason that they would have mirrored the astonishing artillery located at nearby Fort Zachary Taylor. Aside from guns, the design of the towers called for four openings at the top from which soldiers would be able to fire small arms or pour hot oil on invaders.
When construction began on Fort East Martello in 1862, the United States was embroiled in the Civil War. Despite the fact that the Union controlled the island during the war, Key West’s inhabitants were deeply pro-Confederate. This resulted in tensions among slaves, free blacks, the pro-Confederate population, and the U.S. Army, all of whom were involved in the construction the forts. This turmoil, along with the rough environmental conditions of the Florida Keys, impeded construction on numerous occasions.
In 1862, work began on both West Martello and East Martello, although a yellow fever outbreak in July of that year significantly impacted the workforce causing the projects’ carpenters to switch from fort construction to fabricating coffins for the deceased. When the temperatures cooled in October, workers’ health improved and operations resumed. Within a year, the citadel at West Martello was completed while East Martello’s masonry and concrete gun platforms were set.
Once again, yellow fever disturbed construction progress in June 1864 and took a heavy toll on the Army soldiers building the forts. Despite the setback, building work continued, eventually resulting in the near-completion of the cisterns, lower floors, stairways and the advanced batteries. Further setbacks the following year hindered progress, the most significant of which was a devastating hurricane in October 1865 that destroyed components at both forts and threw the remaining construction plans into limbo. A little over a year later, construction on both forts halted, leaving both in an unfinished state.