On Sunday morning, July 30, 1916, at 2:08 a.m., one of the worst terrorist attacks in American history took place at Black Tom Island, New Jersey, a shipping facility located in New York Harbor. Under cover of darkness, German agents detonated more than 2 million pounds of ammunition that was awaiting shipment to England. The explosion—the equivalent of an earthquake measuring 5.5 on the Richter scale—was felt and heard as far away as Philadelphia and southern Connecticut. Windows were shattered across Manhattan, Brooklyn, and Jersey City, and to this day the torch of the Statue of Liberty remains closed to visitors due to the damage it sustained from flying shrapnel. Amazingly, though dozens of dock workers, fire fighters, and civilians were injured, fewer than 10 people lost their lives in the blast.

Initially, the cause of the explosion was unclear. Almost before the fires were extinguished, however, multiple explanatory theories were put forth, with hypotheses ranging from the spontaneous combustion of unstable munitions to sparks from a passing freight train. Some initial evidence seemed to point to dock workers who, in an effort to ward off the clouds of mosquitoes that swarmed the waterfront, had carelessly lit smoke pots, sparking fires that subsequently ignited the ordnance. Most Americans, though, goaded by sensational stories in the press, soon began to subscribe to a more sinister line of speculation: that is, that German operatives or sympathizers had blown up the ammunition to prevent it from being shipped to, and used by, the Allies.

From the outset, Kaiser Wilhelm II and his government steadfastly denied any involvement in the matter. Nevertheless, the extensive media coverage of the Black Tom incident, coupled with other contemporary reports of espionage and sabotage activities on American soil, helped to further turn public opinion against Germany and her allies. Within a year, angered by a series of real or perceived violations of its sovereignty, the United States declared war on the German Empire.

But this was not the end of the Black Tom Island story.

After the war’s end, the German-American Mixed Claims Commission—the organization charged with assessing war reparations—launched an inquiry into the cause of the blast. Over the next decade and a half, investigators sifted through a mountain of less-than-conclusive evidence, finally ruling in 1939 that Germany had, indeed, supported the attack. By then, however, with another world war looming, the German government under Adolf Hitler was less than inclined to pay the United States $50 million in damages. Ultimately, another 14 years would pass until the two countries agreed that Germany would reconcile all of its outstanding war reparations claims, including those resulting from the Black Tom explosion. The final payment of the settlement was received in 1979, at last bringing the issue to an overdue, official close. Today, the events of July 1916 are commemorated by a memorial at Liberty State Park in Jersey City, New Jersey, which informs visitors that they are “walking on a site which saw one of the worst acts of terrorism in American history.”

For contemporary accounts of the Black Tom Island explosion, New York City newspapers such as The New York Herald Tribune and The New York Times serve as an excellent resource. For more recent treatments of the subject, see journalist Harold Blum’s, Dark Invasion: 1915: Germany's Secret War and the Hunt for the First Terrorist Cell in America, which provides a thorough account of covert German espionage and sabotage operations in the United States during World War I. Other noteworthy treatments of the topic include The Detonators: The Secret Plot to Destroy America and an Epic Hunt for Justice (2006), by Chad Millman, and Jules Whitcover’s 1989 work, Sabotage at Black Tom: Imperial Germany's Secret War in America, 1914-1917.