British forces in Malta are preparing ammunition stocks to be sent to Sicily, after ammunition there had run low since it had been used to relieve the defending garrison of Gaeta which had been under siege by the French.
The main gunpowder store in Birgu is located in a casemate within the city walls, close to the Porta Marina.
This is an improvised measure since the casemate had not been intended to be used as a gunpowder magazine, but such practice is common at this time and gunpowder is also stored in casemates at other locations such as Fort St. Angelo, Fort Ricasoli and Mdina.
The Birgu magazine is located close to civilian housing, and the residents have complained about the dangers.
Although preparations have been made to find alternative sites, nothing had been done since the storerooms meant to store gunpowder are being used as barracks or military hospitals.
On July 18, the garrison gunner, one Anderson, along with a working party of thirteen men, is preparing a consignment of shells from the Birgu magazine, which is filled at full capacity with three hundred and seventy barrels containing forty thousand pounds (eighteen thousand kilograms) of gunpowder, as well as sixteen hundred shells and grenades .
Anderson is using a metal chisel to remove the fuses from live shells, which is contrary to instructions, and this results in sparks that cause a massive explosion at 06:15.
Anderson and the working party are killed immediately, as are three British soldiers of the 39th (Dorsetshire) Regiment of Foot and twenty-three Maltese soldiers of the 2nd Provincial Battalion.
Around one hundred and fifty to two hundred civilians from Birgu are also killed.
About one hundred others are injured by falling debris.
The explosion frightens the inhabitants of Birgu, and it is also heard in the nearby cities of Senglea and Cospicua, as well as in the surrounding villages.
Since the magazine was located within the city's fortifications, a section of the walls "went up in the air" and left a large breach.
The Porta Marina, one of the city's four gates, along with a small bastion and part of a curtain wall are destroyed, and they will never be rebuilt.
Parts of the Navy Store Houses sre also damaged or destroyed during the explosion
Birgu's cityscape is also altered by the explosion, since a large number of houses are destroyed or damaged, both by the explosion itself and by the rocks which fall from the bastions.
Four hundred and ninety-three people report property losses due to the explosion.
The area which suffers the most severe damage will subsequently become known as l-Imġarraf (Maltese for "the destroyed").
Victims and their families will be paid partial compensation, and Civil Commissioner Alexander Ball
will set up a committee overseeing aid distribution.
He will also urge the government to pay full compensation.
This will initially be denied, but eventually the poorer classes will receive a compensation equivalent to two thirds of their property which had been destroyed, while those of the upper classes receive half of the value of their property.
In 1811, the sum of £18,066.5s.10d is evenly distributed among those who had claimed damages.
A certain wine merchant, Mr. Woodhouse, loses a large amount of wine and the government provided him with extensive storehouses at the former Slaves' Prison in Valletta as a compensation.
This is not the first time that a gunpowder disaster has occurred in Malta.
On September 12, 1634, a gunpowder factory in Valletta accidentally blew up, killing twenty-two people and causing severe damage to the Church of the Jesuits and the nearby college.
In 1662, gunpowder stored in an echaugette on one of Valletta's counterguards blew up after being hit by lightning, but there were no casualties.
