Standards around handling gunpowder were lax in the early 19th century. In the Netherlands this led to the Leiden explosion that rocked the city. The authorities immediately covered up the truth behind this catastrophe.

In 1807 the Netherlands were not quite independent as they were a vassal state of France. Napoleon Bonaparte had installed his brother Louis as a King and the Netherlands was at war with England.

See my article about how the British legitimately took control of the Maltese islands for more about the Napoleonic wars.

The Dutch high command expected a British invasion at any moment. When gunpowder stocks ran low in the city of Delft, the government rented 3 ships to transport more. The captains of these ships were Simon Kortleeven, Cornelis van Doorn, and Adam van Schie. They were all experienced in transporting gunpowder. Adam fell ill at the start so he hired a servant, 25-year old Jan van Engelen, to take his place. He sent his son, Salomon, along too. Salomon took his 15-year old brother with him. The government sent one man, Bartholomeus Hendrik Bobbink to oversee all three ships¹.

On Monday 12 January 1807 at 16:15 a ship containing 18 230 kg of gunpowder exploded in Leiden.

On Tuesday 6 January 1807, the first ship arrived in Amsterdam. The “Delfs Welvaaren” took 738 barrels of 100 pounds weight of gunpowder on board. This is about 18 230 kg. The gunpowder was a mix of artillery powder and a finer type of gunpowder suitable for handguns^{1 2}.

Government official Bobbink told the Delfs to head to Leiden and to wait outside the city for him. He went north with the other two ships to monitor their loading. The idea was the three would meet up outside Leiden and continue to Delft together¹.

The van Schie brothers and van Engelen aboard the Delfs made good time. They arrived outside Leiden on Saturday morning. Over the weekend the brothers visited their sister who lived in Leiden. Van Engelen guarded the ship and its cargo because he had some injury so he couldn’t walk far anyway¹.

Meanwhile the canals froze and Bobbink couldn’t advance any further for the time being. Frustrated but helpless, Bobbink asked the van Schies to continue to Delft¹.

On Monday morning the ship entered Leiden. We don’t know why the crew decided to enter the city instead of continuing their trip to Delft. We know they moored in the Steenschuur canal in a residential well-to-do neighbourhood. This was close to the van Schie sister’s place round the corner from the canal.

At 16:00 that day, witnesses saw the elder brother working on deck talking to the other two who were in the hold¹.

The explosion

At 16:15, the ship exploded. It was full so it had 18 230 kg of gunpowder on board^{1 2 3}.

If you light a small amount of gunpowder with a flame it burns without doing much harm. In large quantities gunpowder explodes. In Leiden the following happened¹:

• A fireball made up of combustion gases formed. The diameter of this fireball in Leiden was 50 m.
• The gases expanded faster than the speed of sound. This is what causes the ‘boom’ in an explosion. It’s a shockwave that hits the surroundings before anything else does. It makes buildings collapse and shatters glass. This time of day is dusk in January and many people were already indoors at home.
• A strong gust of wind followed the shock wave. We don’t know how fast this was going. Based on scientific study of gunpowder it was several hundreds of metres per second. This is tornado-level gusts of wind.
• A small part of the energy from the explosion causes a ground shock in normal cases. Since the Leiden explosion took place on a boat there was no such crater. It’s not clear if there was any effect on the river bed.
• Fragments of the ship shot out at speeds of up to 300 metres per second (984 feet per second). Many of them were later found either east, or west, of the ship which roughly follows the path of the canal. The anchor landed 900 metres away. A 300 kg lead weight which was the counterweight for the mast launched at a speed of 100 metres per second. It landed half a kilometre away.

Survivors collected fragments of wood and metal as souvenirs. They handed them down from one generation to another as mementos. Some are now in the municipal museum¹.

The impact on Leiden

154 people died with the blast and a further 2 000 were injured^{1 2 3} . Most people died because the buildings collapsed on them. The explosion destroyed all buildings within the blast radius, a circle measuring 55 000 square metres. In one case, a nearby school collapsed killing 30 children inside. All windows in the whole city shattered. Dislodged roof tiles littered the streets. There was considerable damage everywhere¹.

Opposite the ship the Van Struijk household was hosting a family reunion. The couple who lived there were hosting their beloved daughter and son-in-law who were showing off their new-born daughter. The only person pulled out of the rubble was an injured maid who lamented, “Why couldn’t I remain with the deceased!”¹

Not very far away, on the now pedestrianised Breestradt, a toddler died but not because of the blast itself. Her older sister was carrying her and, in fright at the sound of the explosion, dropped the infant to the ground killing her on impact¹.

King Louis Napoleon arrived in the city later that evening. He personally assisted with the recovery operations¹. He ordered soldiers on the coast to stop watching for a British invasion and help Leiden instead. He donated 30 000 guilders from his own pocket to support the city. (This is about EUR 305 000 in today’s money.) He also waived all income tax for a 10-year period. Locals took to calling him Louis the Good after these acts of generosity².

King Louis the Good donated EUR 305 000 of his own money

The council wanted to assess the damage but surveyors didn’t have up to date maps. The best they could do was work on a map from 1675 – more than a hundred years old! Analysis of the destruction and annotated maps confirms all houses within 109 metres of the explosion were destroyed. Between 109 metres and 168 metres buildings were damaged beyond repair. A poorer neighbourhood lay south-east of the ship and was almost completely destroyed. Since these buildings were in worse condition this is not surprising¹.

Leiden University rushed out plans to build a new college on the wastelands around the canal. Government was ready to build a shiny new army barracks and a new covered corn-market. The cost of repairing the disaster was high and the town was bankrupt. No redevelopment happened on the area locals now called “The Ruins”. It took till 1836 before some construction started on a new Roman Catholic church¹.

The investigation

The government first concluded this was an act of British sabotage. It didn’t take long before the Minister of Justice blamed the crew’s irresponsible behaviour¹.

Eye-witnesses testified they saw someone throw potato peels thrown overboard moments before the explosion. Mr Jan Overduin was dredging the canal about 100 metres away and he confirmed he saw the crew preparing food on board. He also testified there were two explosions. The first lifted the mast into the air while the second more powerful one hit a fraction of a second later¹.

On the basis of this testimony the authorities concluded the crew’s carelessness caused the explosion¹.

The newspapers ran stories of how old man van Schie was drunk and forgot to extinguish his pipe before going below deck. They must have used details from official paperwork because we know van Schie sent his sons. For 200 years many people repeated this and kept blaming Mr van Schie senior for the disaster¹!

The eyewitness’ account of two explosions is interesting. If the entire cargo exploded it would have exploded at once. Two separate ones suggests something else. One hypothesis is the crew opened one of the barrels and that exploded first. Gunpowder was expensive and there was a thriving trade on the black market. If they opened one of the barrels to steal some, any spark would first cause the exposed powder to explode¹.

The authorities did consider this possibility but discarded it when they realised all three crew died. How can you sell something on the black market if you’re dead? Papers in the Dutch archives show the state prepared a case against the warden at Delft. Police suspected him when the War Office didn’t have proof of the quality of the gunpowder. They arrested the dodgy warden and interrogated him on 13 January. Three days later government inspector Bobbink was also arrested. State’s evidence showed the two worked with lax safety measures to cut down on costs¹.

The police also accused them of transporting two different types of powder at once. The paperwork showed two independent trips for each kind of cargo. Bobbink claimed he was following orders. The warden did too, but his superior was Lieutenant-Colonel Muller of the Bureau of Artillery who denied everything. As an officer, Muller could not be interrogated so they accused the warden of ‘neglect of duty’ on 26 February. Police recommended he be charged in court¹.

On 11 March the case was dropped. The Supreme Court of Holland recommended the warden get his job back. They closed the matter and stored the case files in secret archives¹.

We don’t know what caused this sudden change of heart. One working hypothesis focuses on the contract the War Office had with gunpowder manufacturers. With this contract the government accepted all risk during transportation of explosives. If this ever came to light the government would have been liable for all the damage in Leiden. This would have crippled the government. If the state had continued with a criminal trial this information would have become public¹.

Conclusions

No one was found guilty of the explosion¹.

References

1. Leiden disaster of 1807, The; H.J. Reitsma and A. Ponsen; Icon Volume 13; 2007[↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩][↩]
2. The Pieterskerk nearly 900 years in the heart of Dutch history; Pieterskerk.com; (Retrieved 2018-11-09) [↩][↩][↩][↩]
3. Leiden Gunpowder Disaster Memorial; Atlas Obscura; (Retrieved 2018-11-09) [↩][↩]

Remember: links were correct at time of publication.