A bird’s-eye view of the City of San Francisco, rendered in 1868. Alcatraz Island is clearly visible at the center of the bay with a dense crowd of vessels congregating at the city’s eastern crest.

By 1849, the Port of San Francisco had become tremendously active. Establishing a lighthouse became an immediate priority, to help ships navigate into the new western shipping harbor. Since the military had not yet begun development of the island into the promising military fortress that it would become, the construction of the first western lighthouse was contracted to a Baltimore firm. The crew arrived in San Francisco on January 29, 1853 and immediately began work. The design was for a Cape Cod style two-story cottage with a central light tower and the fifty-foot lighthouse was to be painted white with black trim. The fixed third-order lens did not arrive until October of 1853, and budget problems would delay its installation until June 1, 1854. A fog bell would be added in 1856, after it became clear that frequent fog layers often rendered the light ineffective. The original fog bell had to be rung by hand, but later versions were equipped with a clockwork mechanism that automatically struck the bell at prescribed intervals. As the city of San Francisco continued to grow, a new flashing fourth-order lens was installed, which aided mariners in distinguishing the lighthouse from the city lights.

Alcatraz was the site of the first lighthouse on the Pacific Coast, which commenced operation on June 1, 1854. The structure featured a Cape-Cod-style two-story cottage with a central light tower. The optical lens concentrated the luminance from the flame of a whale-oil lamp into a powerful beacon that could be seen from nearly twenty nautical miles out at sea. The small signpost visible next to the planter indicates that this building also served as a post office.

A full view of the original lighthouse, surrounded by the fort’s arsenal of cannonballs. A close study shows what appear to be children and their mother (left) sitting atop the pile of fifteen-inch cannon balls, each of which weighed over four hundred pounds. Also visible (far left) is the post headquarters.

An early San Francisco defense map drawn in 1863 shows cannon firing ranges from various strategic locations. As the port and city of San Francisco continued to flourish, the military established a concentrated system of fortifications to protect the prosperous settlement. Clearly visible is the triangular defense pattern, which was anchored by the strategically located Alcatraz. Hostile ships entering the harbor would first come under fire from both Lime Point and Fort Point, and would eventually progress into the operative firing range of all three positions. It was an effective and lethal schematic.

On November 1, 1850, a joint Army-Navy military commission presented a report detailing a military defense plan to guard San Francisco from unfriendly powers. Their report stated: “The first consideration in conjunction with defense would be to prevent the passage of hostile vessels through the channel of entrance.”  This would be achieved by creating two lines of defense:

“The outer one at the Golden Gate to consist of a fortress at Fort Point of one hundred and fifteen guns and a battery of one hundred guns directly opposite on Lime Point; the inner to consist of a fortress at Alcatraz with batteries at Black Point (now Fort Mason), and Angel Island.”

The aim was to create a gauntlet of cross fire, which could pour down a continuous barrage of shell all the way from Point Lobos to Telegraph Hill, a distance of about seven and a half miles – which no vessel of the day could survive. In its report, the commission urged immediate development of the fortresses to solidify authority and enhance protection of the infant U.S. territory.

By 1851, the United States had started preparing detailed plans for the three new forts and batteries. The Pacific Army of Engineers arrived at Alcatraz in the winter of 1853, and began to finalize specific plans for the development. Construction at Alcatraz would commence in 1854, with a $500,000 appropriation from the U.S. Congress. In his first report to Washington, Major John L. Smith gave a description of his initial surveys, writing: “The island of Alcatraces is a mass of rock with a very thin layer crust of soil and bird manure on the surface.”  Construction at Alcatraz would commence only months later. First Lieutenant Zealous Bates Tower had been assigned to manage the building of the fortress at Alcatraz, along with his assistant, Second Lieutenant Frederick Prime. The topography of fine-grained sandstone proved to offer more challenges than was originally predicted. Tower would report:

The island is rougher than I anticipated, very rough, steep, and broken on the Eastern Portion of the North West Battery and where the three gun battery is designed to be placed... The sandstone composing the island is very friable; even where hardened on the surface it can be cut with a hatchet. Wrought iron spikes can be driven into the Rock without much trouble... During the month of October, I expect to finish all of the temporary buildings required for the rapid progress of the work, including water tanks, to build the wharf, to prepare the road at least as far as the guardhouse and to make good progress on the ditch of the South Battery.

A military diagram created in September of 1855, illustrating the plans for the fortification and construction in progress. First Lieutenant Zealous Bates Tower supervised the building of the fort in 1854, and later reported that the terrain of Alcatraz was much rougher than he had expected.

An 1870 Eadweard Muybridge photograph of “Pirate’s Cove,” which is located on the western side of Alcatraz. This photograph illustrates the island’s primitive terrain, which discouraged boat landings. Much of the current geographical contours are the result of blasting and reshaping efforts by the early Army Engineers.

The task of converting the Rockinto a sound fortress entailed a series of hardships for labor crews. On July 9, 1857, when three men were excavating the cliff between the wharf and the guardhouse, they unleashed a massive landslide. Two of the men, Daniel Pewter and Jacob Unger, were fatally trapped under the loose debris while the other worker escaped with serious injuries. They would become the first ever fatalities on Alcatraz. During the construction, it was found that the Rock mineral proved to be too frail to be used in the fortification and this necessitated the importation of stone from as far away as China. Granite that was ordinarily used as ballast on ships was also apparently employed in the construction. Masons used a high grade of brick, set in heavy concrete forms to create a dense shield of armor against enemy ammunitions. Construction crews also dug well-concealed tunnels that offered safe storage for cannon powder and other munitions . There were specialized furnaces designed to heat incendiary shells, which would be fatal toward fire-prone wooden ship hulls.

A communication tunnel that was excavated in 1873. The 180-foot tunnel was used as a passageway between two batteries by soldiers during the military era. The Bureau of Prisons sealed the tunnel in 1936 to alleviate the risk of inmates using this passage as an escape route.