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Timeline Mystery: Did a World War I U-Boat Engage in an Artillery Battle with Fort Hancock?

The famous Prussian General Carl von Clausewitz is credited with first articulating the phrase, “the fog of war.” He had observed that during a clash of armies it is often impossible for leaders to know precisely what is going on at any given time, or to know for certain what happened after the shooting stopped, as battles often seemed to occur in dim light or fog.

The “fog of war” would apply both literally and figuratively in one of the more curious episodes of World War I in New Jersey. Here are the facts:

In August of 1918, the tide had turned against the Germans and their allies in the war, which would end with the Armistice in just three months’ time. But German submarine attacks continued on American shipping along the U.S. Atlantic coast, which was almost defenseless against submarine warfare. Dozens of ships were sunk, with attacks off Cape Cod, New York Harbor, Barnegat Light, North Carolina, and elsewhere. 

For example, on August 12, 1918, at 8:00 a.m., the armed Norwegian steamer SS Sommerstadt was sunk by a torpedo fired from a German submarine 25 miles southeast of Fire Island.

The following day, August 13, 1918, at 6:10 p.m., the SS Frederick R. Kellogg, an American oil tanker, was also torpedoed and sunk by a German submarine, this time ten miles off Barnegat Light, about 100 miles from where the Sommerstadt was sunk.

The submarine in both instances later turned out to be SM U-117, a Type UE version of the famous German submarine, adapted for laying sea mines. Some mine-laying submarines did not feature deck guns, but SM U-117 was armed with fore-and-aft 15cm (5.9″) guns.

These are accepted facts, and neither event has anything to do with Monmouth County. The question is, what was SM U-117 up to during the 34 hours in between the two sinkings?

According to the Asbury Park Press, residents claimed that on the afternoon of August 13, during a thick fog, something engaged the heavily fortified and armed U.S. Army defenses at Fort Hancock in a back-and-forth artillery barrage:

Sound of Firing Heard

Residents along the shore yesterday afternoon heard the great guns at Sandy Hook firing, and in addition to the rumble of the giant discharges, thought they could distinguish between the burst of shells. Between 3 and 4 o’clock, apparently off to sea to the northeast, came the sound of what seemed to be bursts of firing, from three to six shots being heard, repeated at intervals of 10 to 15 minutes. The firing caused little comment, it being presumed it was the often heard practice firing at Fort Hancock.

After the end of the war, the Press ran a front-page follow-up story that claimed a submarine crept up in a fog and hurled 16 shells at Fort Hancock, but without doing any damage. According to “confidential advises, which the end of war now releases,” the Press stated that:

…the shells dropped near the extreme end of the Hook, near the Coast Guard station. One of the shells is said to have landed within 50 feet of the guard station.  Lookouts swept the waters with their most powerful glasses but the fog bank was impenetrable.

And from all that, the Press concluded that the bombardment that was heard and experienced by Monmouth County residents involved a U-boat. But no submarine was ever seen by anyone on land that day.

If the Press version is accurate, it may be one of the only known occasions in which a German submarine engaged in combat against a land-based military installation during World War I. SM U-117 had a clear charter to engage in warfare against shipping, and the submarine had been very successful since initiating attacks on the U.S. Atlantic coast, sinking 11 ships just on August 10 and 11. She would go on to sink 20 ships in the month of August alone using deck guns, mines, explosives, and torpedoes.

The witness accounts seem credible, and yet it is very difficult to fathom why a U-boat captain would do such a thing. And it is curious that no other account of this seems to exist anywhere, either in other newspapers, U.S. military reports, or official German submarine records.

This Timeline Mystery examines the details surrounding this event to see if it is plausible that a World War I U-boat faced off in the fog against a heavily armed and fortified military installation.

Deadly Weapons of War

In World War I, German submarines typically inflicted damage on enemy vessels in three ways. The most prevalent method was to attack typically unarmed merchant ships using deck guns while on the surface, diving afterward to evade detection and counter-attack.

On other occasions, German submarine sailors would board the enemy vessel and place timed explosives that would detonate after the sub was safely away. Torpedoes were generally saved for armed vessels and warships or when surface combat was untenable. Some U-boats were also equipped to lay sea mines in busy shipping lanes.

SM U-117 was a Type UE 2 submarine. Type UE 2 U-boats were typically armed with 14 torpedoes, 42 mines, and 494 rounds of 150mm shells for deck guns that had a range of up to eight miles. Explosives that could be set with a timer were also on board. She was capable of speeds of 17 mph (14.7 nautical mph) while on the surface.

The timing of this event is tricky, but seems plausible. Fire Island is approximately 50 miles from Sandy Hook as the crow flies. The Sommerstadt was sunk about 25 miles off Fire Island, so SM U-117 was about two hours away from Sandy Hook at that time. The Kellogg was sunk approximately 10 miles off Barnegat Light, which is about 50 miles south of Sandy Hook. At full speed, SM U-117 would have needed about 2.5 hours to travel 50 miles on the surface. But the Kellogg was attacked at 6:10 p.m., so if we are looking for reasons to believe this story is true, we can accept that perhaps the sub left Fort Hancock closer to 3:45 p.m., in which case the distance traveled over the time limit is possible. All of these times, ship attack locations, and distances, are approximate, and the actual time and distance parameters may be different but based on reports at the time, it is by any estimation a tight time window for these two events to have happened when witnesses say they did, if they involved one U-boat.

It’s also important to keep in mind that it was a dead-flat calm day, the ocean like a mirror, with a thick layer of fog. Survivors of the Kellogg said that due to the flat calm water, any submarine surfacing or even raising a periscope would have been easily noticed, but nothing was seen at any time. Those on board were caught completely by surprise when the torpedo struck.

If SM U-117 was submerged as it approached the Kellogg, so as to be undetected while making an attack run, it makes it even more difficult to fit within the time frame, as underwater speeds for a Type UE U-boat were less than half that of surface speeds. If any part of the trip from Sandy Hook to Barnegat Light was submerged, then either the shore residents are mistaken about the time frame for the artillery barrage, or else it was some other entity that threw 16 shells at Sandy Hook.

Fort Hancock in World War I

As the primary defense installation guarding the entrance to New York Harbor, considered the most important strategic port in the U.S. at the time, Fort Hancock had expanded into a formidable arsenal of guns, mortars, and howitzers designed to destroy any attacker, from the largest dreadnaught battleships to the fastest torpedo boats.

In World War I, Fort Hancock defenses largely consisted of an array of concrete gun batteries, which mounted the most modern and powerful cannons of the day. These gun batteries were designed to blend into the seashore environment for protection and camouflage.

Using counterweights, the guns were lifted through openings on the roof, and could fire armor-piercing projectiles as far as seven miles. After firing, the gun platforms moved back down inside for reloading. The procedure made the guns disappear from the enemy’s view, and soldiers called them “disappearing guns.”

In 1918, Fort Hancock boasted seven counterweight-type disappearing gun batteries, mounting a total of 16 guns including 6-, 8-, 10-, and 12- inch caliber cannon.

Sandy Hook was also the site of America’s first mortar battery. Complete in 1894, it mounted sixteen 12-inch caliber breech-loading rifled mortars, which were divided equally in four massive concrete and earth-covered “firing pits.” The mortars were designed to fire armor-piercing projectiles, weighing up to 1,000 pounds, in high arcs to bombard an approaching enemy battleship or cruiser from above.

Fort Hancock’s defenses also included smaller gun batteries that mounted 3-, 5-, and 6-inch caliber guns. These weapons could be loaded, aimed, and fired quickly to sink small, fast enemy warships like destroyers and torpedo boats. From 1898 through 1904, five rapid-fire gun batteries were built on Sandy Hook.

As a result of this tactical plan, a submarine approaching Sandy Hook and Fort Hancock would not necessarily have been able to discern that there was a military installation there, especially on a foggy day. But it is inconceivable that German charts did not include the primary defense fortification on that part of the east coast. Whether a captain could see the guns or not, there is little question that they were aware that this was hardly a defenseless lighthouse. This was, in fact, the most heavily defended place on the Atlantic coast, possibly the most heavily defended place in all of North America in 1918.

This voyage to the Atlantic coast of the U.S. was SM U-117’s one and only patrol mission. So if you are captain of this U-boat, and you have had immediate success from the very first day you began attacks off Long Island, what on earth would make you deliberately risk a potentially hellacious counter-attack just to lob 16 shells that failed to land anywhere near a gun battery? Further, while the guns of Fort Hancock and those of SM U-117 had approximately the same maximum range of about eight miles, the firm foundation of concrete, combined with the ability to use triangulation for precise aim, gave Fort Hancock’s guns a significant advantage in accuracy compared with the floating, rolling, pitching, moving deck of a submarine at sea. Any gun that is moving while being aimed is unlikely to hit its target unless at close range. That’s exactly how U-boats typically used their deck guns, at close range.

Three things strongly suggest that whatever did happen on the afternoon of August 13, 1918, it was not SM U-117 firing its weapons:

  1. There are no reports anywhere of any attacks by German submarines against any kind of land-based targets in World War I. U-boats did not just cruise around doing whatever they wanted, they were centrally controlled and followed very specific mission instructions. If SM U-117 attacked Fort Hancock, it had to be part of the plan, but no such plan seems to have existed for any other U-boat at any time.

  2. If land-based targets were part of a U-boat’s mission, it’s absurd to think that those targets would include heavily fortified defense installations. Strategic targets on land that could be shelled by a U-boat could include coastal oil refineries, lightships critical to navigators, bridges, ports full of merchant ships…and yet, that never happened.

  3. The distance from Sandy Hook to where the Kellogg sank off Barnegat Light – about 50 miles – is too far for a Type UE U-boat to travel within the time frame established by witnesses, even if cruising at top speed on the surface. Kellogg survivors reported that no submarine was ever spotted, indicating a submerged attack. This makes it even more unlikely that the distance involved could have been covered in the time allotted according to the witnesses on shore who heard the barrage at Sandy Hook.

But if something this outlandish really did happen – a U-boat engaging a major defense installation in a blind exchange of artillery fire – why did no other newspaper ever report it? Why were there no official records that emerged over the years? Surely such an encounter would have meant paperwork for someone at Fort Hancock; such an attack would be documented. No documentation has ever surfaced.

Because SM U-117 was most definitely in the vicinity of Sandy Hook on the day in question, it cannot be determined for certain that this event did not happen. But there are far more reasons to believe that it was something else.

So What Was it if it Wasn’t a U-boat?

As the Press stories make clear, residents of Monmouth County were well accustomed to hearing the guns of Fort Hancock firing. In addition to being a defense installation, Fort Hancock was also site of the proving grounds, where new cannon were tested before being implemented on ship or shore defenses. It’s entirely believable that over the years locals would be able to recognize the unique sounds of the different mortar and gun batteries when they fired their weapons. So we can believe that something did happen on that day. Possible explanations include:

  • Another submarine other than SM U-117 made this assault. Other submarines were operating along the northeast Atlantic, but for reasons stated above, this seems highly unlikely.
  • An armed U.S. vessel of some sort may have seen SM U-117 off Sandy Hook cruising on the surface and fired shots that overflew the target and landed on shore. Fort Hancock guns briefly returned the fire but quickly stopped, ostensibly because no foreign target could be confirmed. Again, the afternoon was marked by almost zero visibility due to fog.
  • New types of guns, ammunition, and weapons systems were being tested all the time at Fort Hancock, meaning that while some guns would have familiar sounds, others would not. In the first Press reports, residents assumed that what they had heard was normal artillery practice at Fort Hancock. In consideration of all the facts, it seems that they were probably correct the first time.

After the end of the war, the captain of SM U-117 surrendered to the U.S. The sub was first used for exhibitions along the Atlantic coast before being sunk on 21 June, 1921, near Cape Charles, Virginia, during aerial target practice tests.


The Defenses of Sandy Hook. (2021). Fort Hancock and Sandy Hook Proving Ground National Historic Landmark. National Park Service, U.S. Department of the Interior. Available:

Did Daring U-boat Shell Sandy Hook? (1918). Asbury Park Press, Asbury Park, N.J., November 18, 1918, P. 1.

Helgason, Gudmundur. (2021). WWI U-boats, U 117. Available:

How far is it? (2021). Distance Calculator. Available:

German Submarine Sinks Steamer at Very Gates of New York Harbor. (1918). Asbury Park Press, August 14, 1918, P. 1.

Germany. (2021). NavWeaps. Available:

Images: By USN –, Public Domain,

4 thoughts on “Timeline Mystery: Did a World War I U-Boat Engage in an Artillery Battle with Fort Hancock?”

  1. Is out possible the U-Boat was unaware of the battery but aware of the ammunition caches at Fort Hancock and attempted to hit one or more?

    1. Well everyone knew about the battery because they were testing large guns all the time, so it’s difficult to believe any German sub captain was unaware of what at the time was possibly the most heavily armed and fortified defense installation on the Atlantic Coast. But let’s say you’re right, because we DON’T know. In that case, given the zero visibility at the time, I wonder how a U-boat captain could know where to aim to hit ammo caches. SOMETHING happened on that day. But given that the sub captain surrendered to the U.S. after the war, once again, it would seem that this would have come to light as he was doubtless interrogated after his surrender. I guess I’d need to know more about where ammunition was stored at Fort Hancock at the time to be more certain either way. But, either way, thanks for your comment!

      1. I’m actually writing a book about this entire topic and can tell you with confidence that U-117 (or any any other German submarine for that matter) did not fire on Sandy Hook, in fact, she was already outside of Lavallette in the early afternoon hours that day. The initial report was actually accurate, what residents heard was just routine fire from the Fort or the proving grounds on the north end of the hook. Interestingly, the proving ground was known for misfires, ricochets, and badly aimed ordnance that often fell within Fort Hancock. It was an issue that was constantly being complained about, but was deemed impossible to fix. Sure enough, that same August of 1918 shells (some as large as 10″) landed in a dangerous proximity to the barracks and other fort structures. In all likelihood, someone saw the craters left by these “friendly” shots and thought it’d be a better story if a German U-Boat’s deck gun was the source. Best Regards.

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