The sound of the blast was unearthly, and the tremor was felt 100 miles away in Philadelphia. The night sky over New York Harbor turned orange. People were jolted from bed and windows shattered within 25 miles. The Statue of Liberty, less than a mile away, was damaged by a rain of red-hot shards of steel. Frightened immigrants on Ellis Island were hastily evacuated to Manhattan. The epicenter of the blast a small island called Black Tom all but disappeared in what was then the largest explosion ever in the U.S., on Sunday, July 30, 1916 at 2:08 a.m. It destroyed about 2,000 tons of munitions parked in freight cars and pierside barges, awaiting transfer to ships and ultimately destined for the World War I battlefields of France. http://www.cbsnews.com/stories/2006/07/30/ap/national/mainD8J6HG300.shtml
This was 1916... so the Americans were definitely supplying munitions before they entered the war. Was it definitely going to the Allies, or was some of it going to the Germans? Certainly, when the Germans tried using cargo submarines, it was to obtain high value chemicals and tools from the US, and they made at least one successful transatlantic trip.
It was an act of sabotage ( apparently ! ) on American ammunition supplies by German agents to prevent the materials from being used by the Allies ! Interesting about the agents though ... they were caught but were pardoned and released in 1923 !!
