Great Blow

The Great Blow or Great Blowe was a pro-royalist riot and resultant explosion that took place on 24 April 1648 in Norwich during the Second English Civil War. 98 barrels of gunpowder were accidentally detonated in Committee House, causing the largest explosion recorded in England during the 17th century.

The riot can be attributed to many complex causes including excise tax, strict policies upon churches, and impressment. The inciting incident was an 18 April 1648 petition which accused the Norwich Mayor John Utting of helping royalists into local power and requested that he should be taken in custody to the House of Commons in London. A counter-petition from Utting encouraged a royalist riot. The riot spread from the city's market and Chapel Field to the houses of the mayor's supporters and the gunpowder stores in Committee House. The subsequent accidental explosion is due to an unknown direct cause.

Contemporary estimates of deaths caused by the explosion varied between 80 and 200. Forty buildings were destroyed, amounting to an estimated £20,000 (equivalent to £2,840,425 in 2023) of damage. The windows of two nearby churches were shattered by the blast. Eight men were executed for their apparent roles in the riot of the 108 who stood trial; 26 of the others were fined £30, seven were imprisoned and two were whipped. The explosion and its context were named a 'mutiny', 'blow' or 'crack' by its contemporaries.