French sea captain Auguste Bernard Duhaut-Cilly visited the small islet on April 10, 1827, eight years before Dana's voyage. Climbing to its highest point, he discovered something unexpected: the eyrie of a sea eagle with two eaglets, the birds black with yellowish-white patches on tail and head. From this description, the birds were almost certainly bald eagles, then common along the California coast. The island they nested on sat in San Pedro Bay alongside another islet called Rattlesnake Island, which would eventually become the industrial sprawl of Terminal Island. But in 1827, these were wild places, inhabited by eagles and little else.

On October 8, 1846, American soldiers fought local Californios in the Battle of the Old Woman's Gun, a skirmish during the Mexican-American War. As many as six Americans died in the fighting. Their bodies were buried on the islet the Spanish called Isla del Muertos, adding military graves to whatever earlier burials the island already held. The name stuck. Deadman's Island, Dead Man's Island, Reservation Point, it accumulated aliases like it accumulated the dead, becoming a convenient cemetery for a harbor town that had little use for elaborate graveyards.

A whaling station operated on Deadman's Island beginning in 1860. The Los Angeles Star reported in January 1861 that a whaling party from San Diego had located on the island and captured two whales, extracting forty-five barrels of oil. Business improved. In March 1861, they caught a right whale plus five others in two weeks, each estimated at $300 value. The following season brought twenty-five whales, probably grays migrating along the coast. Captain Hart ran the station from 1860 to 1862; Captain Henry Johnson of San Diego backed the operation financially. A second whaling venture tried again in 1865-66 under Captain Jack Smith, lasting only one season before the industry moved elsewhere.

In the late nineteenth century, Deadman's Island became ammunition in the free port wars, a political battle over where to build Southern California's major deepwater harbor. Powerful interests backed either San Pedro or Santa Monica Bay. Senator William P. Frye of Maine, arguing against San Pedro before the Senate Committee on Commerce, seized on the island's ghoulish names. Deadman's Island! Rattlesnake Island! I should think it would scare a mariner to death to come into such a place! The mockery failed. San Pedro won the harbor fight, and plans soon emerged to dredge and expand the port, even if it meant erasing inconvenient geography.

Harold Lloyd filmed the comedy short Lonesome Luke's Wild Women on Deadman's Island in late 1916, one of the last records of the islet as a recognizable landmark. Beginning in 1928, dynamite, dredgers, and bulldozers went to work. The expanded Port of Los Angeles needed the space, and Deadman's Island stood in the way. As workers broke apart the rock, they uncovered up to two dozen skeletons. The dead included the sailors and marines from the 1846 battle, Black Hawk, one of the Native Americans forcibly removed from San Nicolas Island in 1835, two Spanish soldiers possibly dating to the seventeenth century, a blonde woman of unknown origin, and a man with an arrowhead lodged in his skull. The island had served as a burial ground for centuries. Now it exists only in photographs and old charts, a ghost landmark in a harbor that no longer remembers its names.