Today we will be looking at the SS Richard Montgomery, a shipwreck in the mouth of the River Thames.

What makes this wreck particularly remarkable, however, is the presence of a deadly cargo—a stockpile of explosives that, to this day, lies submerged within its fractured hull.

It stands as a haunting testament to the perils of war and the lasting impact it can leave upon the seas.

A Liberty ship built during the Second World War, the Richard Montgomery’s service was tragically cut short when it ran aground in the Thames Estuary off the coast of England.

Today, the SS Richard Montgomery remains a source of intrigue and concern.

The wreck, located just a stone’s throw from busy shipping lanes and coastal communities, continues to pose a potential threat to maritime safety and environmental stability. The question of what would happen if the explosives were to detonate remains a subject of debate and speculation.



The SS Richard Montgomery was an American Liberty ship, built by the St. John’s River Shipbuilding Company in Jacksonville, Florida launched on February 15, 1943. It was named after Irish-born American Revolutionary War general, Richard Montgomery.

Liberty ships were constructed by various shipyards in the United States during World War II to address the urgent need for merchant vessels to support the Allied war effort.

The Liberty Ship ‘SS John W Brown’ gives an idea what the Montgomery would have looked like.

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They were built to ensure a steady supply of troops, equipment, and supplies to the frontlines, sustaining military operations. The production of Liberty ships aimed to compensate for losses at sea due to enemy attacks, bolstering the supply lines and replacing lost vessels.

These ships were constructed following a standardized design, allowing for rapid mass production and the quick expansion of the merchant fleet.

Liberty ships were versatile, capable of transporting various types of cargo, and played a vital role in meeting the diverse logistical needs of the war. Overall, their production was crucial in sustaining the war effort and contributing to the eventual victory of the Allies.

SS Richard Montgomery

The SS Richard Montgomery had a relatively short service history. Constructed by the St. John’s River Shipbuilding Company in Jacksonville, Florida, during World War II, the ship was primarily used as a cargo vessel.

It made multiple voyages across the Atlantic Ocean, transporting goods and supplies to support the Allied war effort, although the specifics of its service history are unclear.


In August 1944, during what turned out to be its final voyage, the ship departed from Hog Island in Philadelphia, loaded with 6,127 tons of munitions.

Upon reaching Southend on 20 August 1944, the SS Richard Montgomery came under the authority of the Thames naval control stationed at HMS Leigh, located at the end of Southend Pier.

The harbour master, responsible for overseeing shipping movements in the estuary, directed the ship to anchor off the north edge of Sheerness, which served as the designated Great Nore Anchorage area.

Here, the ship would await the formation of a convoy to travel to Cherbourg, France which had recently been liberated by Allied forces.

One of the buoys that marks the exclusion zone around the wreck. Image by Gill Edwards CC BY-SA 2.0

There is much debate as to why the Montgomery ran aground, but the generally accepted theory is that high winds caused the ship to drag its anchor.

Then, as the tide receded, the middle of the ship became grounded on the sandbanks near the Isle of Sheppey, about 1.5 miles (2.4 kilometers) from Sheerness and 5 miles (8 kilometers) from Southend.

The spine of the ship broke as it rested on the crest of the sandbank. It was later found that this was a weak spot in the ship’s design.

Efforts to salvage the ship’s explosive cargo began on August 23, 1944, using its own cargo handling equipment. However, by the next day, the ship’s hull had cracked open, leading to flooding in several cargo holds at the bow end.

The salvage operation continued until September 25, but the ship was eventually abandoned after it completely flooded but before all the cargo could be recovered. Subsequently, the vessel broke into two separate parts near the middle still with 1,500 tons of explosives still in the holds.

The Montgomery Today

The wreck now lies in water about 15 metres deep, with its masts always protruding. The ship was later covered under the Protection of Wrecks Act in 1973, instituting a no-entry exclusion zone around the ship and ensuring it was monitored by the Maritime and Coastguard Agency.

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In 1970, a BBC News report revealed the potential consequences if the wreck of the Richard Montgomery were to explode.

It stated that the explosion would create a column of water and debris approximately 300 meters (980 feet) wide, shooting up into the air to a height of nearly 3,000 meters (9,800 feet).

The force of the explosion would generate a wave reaching a height of 5 meters (16 feet).

The impact would be significant, with almost every window in Sheerness, a town with a population of around 20,000, being shattered, and buildings suffering damage from the blast.

The wreck is near shipping lanes and poses a threat to the nearby oil refinery. Image by Christine Matthews CC BY-SA 2.0

It is up for debate whether that is true or an over exaggeration, but in 2012, the estimate was then changed to a 1 meter high wave that would cause some flooding in low level coastal areas.

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The question then becomes: What to do about it? One of the reasons for not removing the explosives from the SS Richard Montgomery is the unfortunate precedent set by a similar operation in July 1967 involving the Polish cargo ship ‘Kielce’, which had sunk in 1946 off Folkestone in the English Channel.

During initial attempts to neutralise the cargo, the Kielce unexpectedly exploded, causing an earthquake-like impact equivalent to a 4.5 magnitude on the Richter scale.

This explosion created a crater 20 feet (6 meters) deep in the seabed and triggered “panic and chaos” in Folkestone, although no injuries were reported.

It’s important to note that the Kielce was located at least 3 to 4 miles (4.8 to 6.4 kilometers) from land, submerged in deeper waters than the Richard Montgomery, and carried only a fraction of the explosives present on the latter.

This incident has contributed to the caution exercised in dealing with the explosives on the Richard Montgomery.

The masts of the wreck are always protruding from the water. Image by Christine Matthews CC BY-SA 2.0

Despite these claims, many believe there is no threat at all, however, the government has laid out future plans for the site, and also ways to limit the threat that it poses, should it be as deadly as it is made out to be.

The exclusion zone is marked by buoys and is under 24-hour surveillance by the Medway Vessel Traffic Monitoring Service, they even have satelites monitoring the area.

The seabed and the wreck itself are surveyed annually using sonar, looking for any changes or degredation to the wreck.

The 2021 survey report stated that  “no significant changes had occurred” since the 2020 survey. One of the more practical plans for the site is the removal of the wreck’s masts, which will put pressure on the ship’s structure – the MoD has planned this for June 2023.

The SS Richard Montgomery stands as a cautionary tale of the potential dangers posed by the remnants of war. Laden with a significant quantity of unstable explosives, the wreck poses inherent risks to maritime traffic, nearby communities, and the environment.

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Decades have passed since its grounding in the Thames Estuary, yet the decision not to remove the explosives stands testament to the fragile nature of the ship.