In June 1916 Kurt Jahnke and Lothar Witzke, two former German military officers turned spies, made their way east from San Francisco to New York. They spent at least some time at Martha Held’s safe house for German spies at 123 West 15th Street in New York and they met with two other plotters, Friedrich Hinsch and Michael Kristoff. Martha Held was a former opera singer whose townhouse in Manhattan was a favorite meeting place for interned German ship officers and the intelligence agents. While at Martha Held’s several meetings were held to plan out the details of how to blow up the munitions depot at Black Tom. Black Tom Island was, by 1916, a peninsula. Originally an island, the Lehigh Valley Railroad had built a causeway out to the island and laid railroad tracks and built piers where barges would dock. There was no gate at the base of the peninsula, just a guard shack that could easily be bypassed. Black Tom also had seven large brick warehouses on it for storing munitions. By Jersey City ordinance, no barge or railroad car containing explosives was allowed to stay at Black Tom overnight; a law that was routinely flouted. There were guards stationed at the base of the peninsula who regularly made rounds of the depot, but the Germans had bribed at least some of these guards to look the other way. On the night of July 29 – 30, 1916, there were approximately 2 million pounds of explosives of various types on Black Tom Island, much of it in the warehouses, but some in railroad boxcars, and about 100,000 pounds on the Johnson Barge No. 17 which was tied up to a dock near the middle of the island. One hundred years later, there is still controversy over who blew up the facilities at Black Tom Island and how they did it. The author Jules Witcover has what is probably the best and most plausible description:
"Witzke and Jahnke came in to the Black Tom terminal over water around midnight in a small boat laden with explosives, time fuses and incendiary devices. Kristoff meanwhile infiltrated the depot from the land side. They then set small fires in one or more of the boxcars containing TNT and gunpowder, and placed explosives with time fuses there. They also planted time bombs and incendiary devices on a barge – the Johnson 17 – that was loaded with more explosives and tied up to a pier at another point off the yard. Then Witzke and Jahnke retreated onto the darkened river to await the outcome of their work and Kristoff fled by land."
About 12:30AM one of the guards discovered a small fire in a boxcar and put it out. Shortly thereafter several other fires were discovered and the Jersey City fire department was called. The fires quickly got out of control and both the guards and the firefighters fled in fear of the possibility of explosions. At 2:08AM the first titanic explosion occurred as the boxcars and then the warehouses started to go. The explosion blew out windows all across Manhattan and Brooklyn on the New York side and through Jersey City, Bayonne and Hoboken in New Jersey. The explosion was heard and felt as far away as Philadelphia. Everyone was awake. About twenty minutes after the first blast the Johnson 17 barge went up in a second gigantic explosion sending shrapnel across New York Harbor, including dotting the Statue of Liberty, nearly a mile away and leaving a 300-foot wide crater on one side of the Terminal. For hours ammunition and charges went off, raining casings and shrapnel down all over the harbor. Miraculously only four people were killed, including the captain of the Johnson 17 who had made the mistake of sleeping on board that night. Black Tom Island and the depot were a complete wreck; it was estimated that the damage caused by the explosions was in the neighborhood of $20,000,000 in 1916 dollars. Here's a picture of the aftermath:
