The "Battle of George Square", also known as "Bloody Friday" and "Black Friday", was one of the most intense riots in the history of Glasgow; it took place on Friday, 31 January 1919. The dispute revolved around a campaign for shorter working hours, backed by widespread strike action. Clashes between the City of Glasgow Police and protesters broke out, prompting the Secretary of State for War Winston Churchill to order soldiers and tanks to the city to prevent the violence from escalating due to fears by the UK government of a Bolshevist uprising. It was described as a "socialist revolution" by supporters, as had happened in the 1917 Russian Revolution, and was occurring in Germany and in the Austro-Hungarian Empire while the 'Forty Hours' strike unfolded.
Before the First World War, the standard working week was 54 hours. National negotiations had established a 47-hour working week for men in the shipbuilding and engineering trades, to be introduced in 1919. A Joint Committee of shop stewards, members of the Scottish TUC and Clyde Workers' Committee however proposed a campaign to limit working-hours to 30 per week, which was altered to 40 per week after the Glasgow Trades Council became involved. It was, however, opposed by the Amalgamated Society of Engineers and most other unions.
The immediate objective was to alleviate unemployment, exacerbated by the post-World War I recession, by sharing out available working hours more widely at a time when unemployment was rising as war contracts were completed and when tens of thousands of ex-servicemen were returning to the civilian labour force. Many workers also resented the fact that the new 47-hour week agreement removed their traditional morning break.
A strikers' meeting was called for Monday, 27 January, and more than 3000 workers gathered at the St. Andrew's Halls; 40,000 Glasgow workers came out on strike that same day. By Friday 31 January, the number had swollen to "upwards of 60,000". It was Scotland's first mass picket since the Radical War of 1820. The strike culminated in a mass meeting in George Square on the Friday to hear Lord Provost Sir James Watson Stewart issue a response from the British government to the unions' request for government intervention in the dispute. Emanuel Shinwell, the Glasgow Trades Council president was amongst those to address the crowd.
The fierce fighting between the City of Glasgow Police and protesters began while a Clyde Workers' Committee deputation was in the Glasgow City Chambers meeting with the Lord Provost of Glasgow. On hearing the ensuing riot that was taking place in George Square, CWC leaders David Kirkwood and Emanuel Shinwell moved outside in an effort to quell the riot. Before they could reach the crowds outside however, Kirkwood was knocked to the ground by police and he, William Gallacher and Shinwell were arrested and charged with "instigating and inciting large crowds of persons to form part of a riotous mob". Sheriff MacKenzie's attempts to read the Riot Act proved unsuccessful as the crowd tore his copy of the Act from him as he was in the process of reading it.
The exact cause of the riot has been disputed – some sources indicate it was caused by an unprovoked baton charge by the police, while others indicate that strikers attempted to stop trams traveling through the square. Pitched battles took place between police and strikers in the streets around the square. Iron palings were pulled up and used as a defence against the police truncheons, while bottles were mobilised from a passing lorry to serve as missiles. The police's efforts to disperse the crowd from the Square were unsuccessful. Eventually there was a re-grouping and the workers began to move off from George Square to march towards Glasgow Green. Police were again unsuccessful in their attempts to disperse the strikers.
For the rest of the day and into the night, further fighting took place throughout the city. Many people, women and children among them, were injured. More than a dozen strikers were taken to Duke Street Prison and later tried at the High Court of Justiciary in Edinburgh.
The failure of the police to control the riot prompted the Coalition Government under David Lloyd George to react, after Scottish Secretary Robert Munro described the riot as a "Bolshevist uprising". The Coalition Government sent 10,000 English soldiers; armed with machine guns, tanks and a howitzer arriving on the Friday night to restore order, the largest deployment of British troops on native soil. A 4.5 inch Howitzer was positioned at the City Chambers, the cattle market was transformed into a tank depot, Lewis Guns were posted on the top of the North British Hotel and the General Post Office, armed troops stood sentry outside power stations, docks and patrolled the streets. They were deployed for a week, to deter any further gatherings.
No Glaswegian troops were deployed, with the government fearing that fellow Glaswegians, soldiers or otherwise, might go over to the workers' side if a revolutionary situation developed. Under the orders of Field Marshal Sir William Robertson, Scottish regiments were transported from other parts of Scotland and stationed in Glasgow specifically to avert this possible scenario. Troops from the Highland Light Infantry were also transported from Maryhill Barracks from Maryhill Central railway station to Buchanan Street railway station but without their Glaswegian men. Other troops, including the Argyll and Sutherland Highlanders, Gordon Highlanders and Seaforth Highlanders arrived from Stirling Castle, Redford Barracks and Fort George into Queen Street Station.
Manny Shinwell, William Gallacher and David Kirkwood were jailed for several months. The striking workers returned to work with the guarantee of a 47-hour week, ten hours less than they were working beforehand.
In the General Election of 1922, Scotland elected 29 Labour MPs, including the 40 Hour Strike organisers and Independent Labour Party members Manny Shinwell and David Kirkwood. The United Kingdom general election, 1923 eventually saw the first Labour government come to power under Ramsay MacDonald. The region's socialist sympathies earned it the epithet of Red Clydeside.