The campaign, led by key WSPU figures such as Emmeline Pankhurst, targeted infrastructure, government, churches and the general public, and saw the use of improvised explosive devices, arson, letter bombs, assassination attempts and other forms of direct action and violence. At least four people were killed in the attacks, and at least 24 were injured.
Both suffragettes and the authorities of the time described the arson and bomb attacks as a terrorist campaign.
The WSPU was not the only militant suffragette group. The Women's Freedom League attacked ballot boxes at the 1909 Bermondsey by-election with acid, blinding the returning officer in one eye and causing severe burns to the Liberal agent's neck.
On 8 December, Davison attempted to set fire to the busy post office in Fleet Street with a burning, kerosene-soaked cloth enclosed within an envelope, but the intended fire did not take hold. Six days later, Davison set fire to two pillar boxes in the City of London, before again attempting to set fire to a post office in Parliament Street, but was arrested during the act and imprisoned.
After 1911, suffragette violence was directed increasingly at commercial concerns and then at the general public. This violence was encouraged by the leadership of the WSPU. In particular, the daughter of WSPU leader Emmeline Pankhurst, Christabel Pankhurst, actively planned a self-described "reign of terror". Emmeline Pankhurst stated that the aim of the campaign was "to make England and every department of English life insecure and unsafe".
In June and July 1912, five serious incidents signified the beginning of the campaign in earnest: the homes of three anti-suffrage cabinet ministers were attacked, a powerful bomb was planted in the Home Secretary's office and the Theatre Royal, Dublin, was set aflame and bombed while an audience attended a performance. One of the most dangerous attacks committed by the suffragettes, the attack on the Theatre Royal was carried out by Mary Leigh, Gladys Evans, Lizzie Baker and Mabel Capper, who attempted to set fire to the building during a packed lunchtime matinee attended by prime minister H. H. Asquith. A canister of gunpowder was left close to the stage and petrol and lit matches were thrown into the projection booth, which contained highly combustible film reels. Earlier that day, Leigh hurled a hatchet towards Asquith, which narrowly missed, instead cutting Irish MP John Redmond on the ear.
The suffragettes invented the letter bomb, a device intended to kill or injure the recipient, and an increasing number began to be posted. On 29 January, several letter bombs were sent to the Chancellor of the Exchequer, David Lloyd George, and the prime minister Asquith, but they all exploded in post offices, post boxes or mailbags while in transit. In the following weeks, further attacks on letters and mailboxes occurred in cities such as Coventry, London, Edinburgh, Northampton, and York, and in Aberdeen, thick black ink was used to obliterate addresses in postal boxes.
On 6 February five postmen were burned, four severely, in Dundee after handling a phosphorus suffragette letter bomb addressed to Asquith. On 19 February, there was a suffragette bomb attack on Lloyd George's house, Pinfold Manor, with two bombs planted perhaps by Emily Davison. Only one exploded, seriously damaging the building but causing no injuries. The explosion occurred shortly before the arrival of workmen at the house, and the crude nature of the timer – a candle – meant the bomb had been likely to explode while the men were present. WSPU Leader Emmeline Pankhurst was arrested for planning the attack on Lloyd George's house and sentenced to three years in prison. Between February and March, railway signal wires across the country were deliberately cut, further endangering train journeys.
In May 1913, the Ashley Road Public School in Aberdeen had its roof destroyed by fire, with arson materials. Amongst the other targets selected by suffragettes were sporting events: there was a failed attempt to burn down the grounds of the All England Lawn Tennis Club at Wimbledon, while a plot to burn down the grandstand of Crystal Palace F.C.'s football ground on the eve of the 1913 FA Cup Final was also foiled.
en.m.wikipedia.org/wiki/Suffragette_bombing_and_arson_campaign