Gunpowder explosions were unique in their suddenness. Floods could be predicted from the level of the Thames and the timing of high tide, epidemics spread gradually, and lightning strikes originated from storms that could be seen and heard in advance. Gunpowder, however, gave no such warnings.


These disasters were frightening because they could not be predicted and therefore avoided. Although they occurred only occasionally, the risk of accidental explosions was ever-present and surely contributed to citizens’ feelings of vulnerability during the Tudor and Stuart periods.

Gunpowder usage

From the early 13th century, when gunpowder was first developed in Europe as an explosive substance, it was used as a propellant for projectiles fired from guns, or for the destruction of vast solid objects, such as buildings or rock formations.

Demand for the substance rose inexorably during the 16th and 17th centuries – thanks, in part, to the great increase in shipping and the expansion of armies and navies. Most large merchant vessels carried some cannon as a defence against privateers and pirates. By the early 15th century guns were being made that were small enough to be fired by a single man and powder was also sold to individual customers, for hand-guns and larger pieces, for self-defence and hunting.

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Fireworks and small squibs [small fireworks that burn with a hissing sound] were also developed. As the Lord Mayor’s Show grew from the late 16th century, it saw the consumption of gunpowder in the many ship’s cannon fired on the river, and fireworks became a central part of the show’s lively entertainments.

Gunpowder was a commercially traded product and England was both a maker and importer. As England’s greatest trading hub, London stood at the centre of the gunpowder trade.

A figure of a dragon breathing fire is attached to a rocket tied to a rope stretched between two buildings in this 1628 woodcut. (Universal History Archive/Getty Images)

A dangerous substance

As well as its explosive power, gunpowder had the significant asset of detonating instantly. Contact with just a spark could ignite the whole charge. Yet this could also be a great danger. While it was stable if left untouched, gunpowder’s remarkable sensitivity to flame made it dangerous to move, store or prepare for use. A moment of carelessness or a simple mishap could have deadly consequences. In 1595 it was described as “an unmerciful thing, if any chimney… should take fire, and sparkes fly, or a flint stone strike fire”.

Safety in handling gunpowder was achieved by storing it in enclosed rooms without naked flames; light would be provided by lanterns placed behind internal glass windows. Those working with gunpowder did not carry or wear any metal objects and wore felt slippers, in case the nails in their boots should strike a spark. Rope, rather than iron hoops, was used to bind gunpowder barrels and wadding was placed around them during transportation.

Woodcut showing a man testing saltpetre, a substance used to make gunpowder and preserve meat. (SSPL/Getty Images)

The government’s stocks of gunpowder were kept in its arsenal in the Tower of London. By the mid-1630s many spaces in the Tower were used for gunpowder storage, including the vault under the Master of the Ordnance’s own lodgings. Powder rooms in the White Tower contained more than 2,100 barrels of gunpowder, and were protected by reducing the window openings to narrow slits.

As it became common for ships to mount artillery, warehouses near the quayside became regular places for storing gunpowder, yet rather alarmingly, the substance was also stored within buildings used for other purposes. In 1612, the Clothworkers Company’s hall in Mincing Lane was described as containing a gallery, on the side of which were a chimney and two gunpowder houses. Even more of a public risk was a warehouse on Tower Hill, where, in 1586, more than 800 barrels of powder were being stored in a place where, “rogues and vagabonds oftentimes lodge in the night and burn straw to warm themselves”.


Despite attempts to store gunpowder safely, accidents were not uncommon. Dangers abounded at ‘gunpowder houses’ within the city where the powder was processed. Not only was there a high risk of accidental ignition, the substance was also prone to spoil, through damp and the deterioration of the mixture.

In a building on Tower Hill in 1552, seven men were killed and eight injured when a spark fell into a container of gunpowder. Just a few years later, in 1560, a gun was fired near premises containing gunpowder in Crooked Lane, just north of London Bridge, detonating two barrels. Four houses were wrecked, with others damaged. Eleven people were killed and 17 more injured.

In April 1583 an explosion in Fetter Lane destroyed not just the gunpowder house it originated in, but also other houses in the street, causing damage over a much wider area. “The monstrous and huge blast of the gunpowder” broke windows in the church of St Andrew’s, 150 yards from Fetter Lane, and at the chapel at Lincoln’s Inn, a quarter of a mile in the opposite direction. Despite the extent of the destruction, only two men and one woman were killed. Others were burned by the flames, or injured by falling timbers in the damaged buildings, yet a child in the building where the explosion occurred escaped unharmed.

The cause of such accidents was rarely known, for those who made the mistake that ignited the gunpowder were generally killed. Yet in the case of Robert Porter’s premises in Tower Street in 1650, the circumstances leading to the disaster were established, although not the immediate cause. Porter had 27 barrels of gunpowder stored in his house. Twenty had been sold to a ship’s master, and as they were to be collected the next day, Porter had left them in the shop rather than the usual safer storage place. The explosion, and the following fire, which raged for two hours, killed 67 people, including the five who lived at the house. Fifteen houses were wrecked in total, and at least 100 more had tiles blown off the roofs, windows broken and other damage. The tower of All Hallows Church, opposite Porter’s house, was so badly damaged that, despite repairs, it had to be rebuilt in 1659.

After the Great Fire of 1666, regulations concerning new buildings were issued, designed to prevent multiple house-fires. Yet in 1715, a blaze in Thames Street spread and destroyed more than 100 houses in the vicinity, as well as gutting the new Custom House. It began when a boy making fireworks in his father’s gunpowder shop accidentally caused a detonation that blew up the house. Just three years later, 17 people were killed in an explosion at a brass foundry in Moorfields, where a crowd had gathered to watch captured French guns being recast.

Explosions also occurred on ships, and as the noise was not cushioned by surrounding buildings, these detonations must have been as alarming to the citizens as those in gunpowder houses or merchants’ warehouses. In 1654, a ship on the Thames blew up when a pot of pitch being heated on deck caught fire. As the flames spread, the crew let the ship drift away from other vessels until it beached on the Southwark side, near St Olave’s church. The explosion when the fire reached the ship's gunpowder “made a terrible noise, and shook the houses thereabouts”. All of the church’s windows were broken and eight people were killed, most of them hit by flying debris. By chance, another ship blew up the following day, damaging houses near the shore.

Even within the Tower of London there were occasional lapses in safety. In 1548 an explosion there killed a prisoner and seriously damaged the structure. The serious risk was underlined again in July 1691, when 2,000 gunpowder barrels fell through a wooden floor in the White Tower. Either the powder did not spill out of the barrels, or there was no spark or flame to detonate it, and so a potentially devastating accident was luckily avoided.

The Tower of London, which was used for storing gunpowder. (Print Collector/Getty Images)

Other cities also suffered from major explosions during the period, including Basel (1526), Luxembourg (1554), Venice (1569), Dublin (1597), Delft (1654) and Leiden (1807). Between 1400 and 1850, there were more than 20 major explosions in European cities and towns.


The catastrophic fall-out of accidents such as these prompted the Privy Council and government to issue orders to make the storage and movement of London’s gunpowder safer. The detonation in Crooked Lane prompted the city’s corporation in 1580 to prohibit gunpowder storage in houses in the city [this was modified three years later to allow 2lbs of powder to be stored at any time, as long as it was kept in powder horns that were not placed near a street frontage]. After the 1650 disaster in Tower Street, parliament ordered the committee of the army and the city’s corporation to consider “the best ways for avoiding all mischiefs and inconveniences that may happen by powder, and other combustible matter, in private houses and other magazines within the city of London”.

From the mid-17th century, gunpowder magazines began to be housed in purpose-built structures, rather than in adaptations of existing buildings. These were designed to minimise the chance of an explosion. They were placed some distance from other buildings and surrounded with an earth bank, limiting the impact should an accident happen. However, most of these specialist magazines were built for the use of the armed forces and the citizens’ militia, not for private stores or trading companies.

A master gunner firing a cannon by applying fire to the breech, in a 1590 woodcut. (Universal History Archive/Getty Images)

Such precautions were often ineffectual, however, because gunpowder was in such widespread use and control of the commercial side of its dealing and transporting was difficult. Even the response to a perceived danger could be lukewarm. In 1635, city justices were informed that a gunpowder house had been moved to a site near Clement’s Inn, close to houses and footpaths, alarming nearby residents and walkers. Yet rather than issuing a peremptory order to close the house, the justices simply decided to inspect it and order its removal if they found it to be dangerous.

A 1719 parliamentary order that restricted the amount of gunpowder stored in a building was equally ineffective. A building could simply be divided by a new wall, thereby doubling the quantity allowed, and subdivided again for further storage. These problems were recognised in a supplementary Act of Parliament five years later, and restrictions on the amount of powder that could be stored were reiterated in 1742.

The incidence of explosions did decline during the 18th and 19th centuries, but the danger had not gone away – there was a detonation on the Regent’s Park Canal as late as 1874.


Stephen Porter is the author of The Story of London: From its Earliest Origins to the Present Day, published in January 2016 by Amberley.