In 1849, a detachment of US Army engineers, including Robert E. Lee, who would later become the commander of the Confederate army, surveyed the area. They recommended Mullet and Egmont Keys become fortified as appropriate site for coastal defense installations. Both keys could only be reached by boat since they were islands off the mainland. Although no fortifications had yet been built, Union troops were stationed on the two keys during the Civil War (1861–1865) to aid in the Union blockade of Tampa Bay, with the Egmont Key lighthouse acting as an observation tower. The keys were again abandoned by the military until 1882 when military reservations were officially created on the two keys. However, it would be several years before actual permanent construction would commence as a result of defense considerations linked to the Spanish–American War.