On 19 March 1921, Tom Barry's 100-strong West Cork IRA unit fought an action against 1,200 British troops – the Crossbarry Ambush. Barry's men narrowly avoided being trapped by converging British columns and inflicted between ten and thirty killed on the British side.
A general election for the Parliament of Southern Ireland was held on 13 May. Sinn Féin won 124 of the new parliament's 128 seats unopposed, but its elected members refused to take their seats.
The biggest single loss for the IRA, however, came in Dublin. On 25 May 1921, several hundred IRA men from the Dublin Brigade occupied and burned the Custom House (the center of local government in Ireland) in Dublin city center. Symbolically, this was intended to show that British rule in Ireland was untenable. However, from a military point of view, it was a heavy defeat in which five IRA men were killed and over eighty captured.
On 6 June 1921, the British made their first conciliatory gesture, calling off the policy of house burnings as reprisals. On the other side, IRA leaders and in particular Michael Collins, felt that the IRA as it was then organized could not continue indefinitely. It had been hard-pressed by the deployment of more regular British soldiers to Ireland and by the lack of arms and ammunition.
Prince Philip of Greece and Denmark was born in Mon Repos on the Greek island of Corfu on 10 June 1921, the only son and fifth and last child of Prince Andrew of Greece and Denmark and Princess Alice of Battenberg. A member of the House of Glücksburg, the ruling house of Denmark, he was a prince of both Greece and Denmark by virtue of his patrilineal descent from George I of Greece and Christian IX of Denmark, and he was from birth in the line of succession to both thrones.
On 24 June 1921, the British Coalition Government's Cabinet decided to propose talks with the leader of Sinn Féin. Coalition Liberals and Unionists agreed that an offer to negotiate would strengthen the Government's position if Sinn Féin refused.
The Communist Party of China was founded by Chen Duxiu and Li Dazhao in the French concession of Shanghai in 1921 as a study society and informal network. Mao set up a Changsha branch, also establishing a branch of the Socialist Youth Corps.
it was decided to hold a central meeting, which began in Shanghai on July 23, 1921. The first session of the National Congress of the Communist Party of China was attended by 13 delegates, Mao included.After the authorities sent a police spy to the congress, the delegates moved to a boat on South Lake near Jiaxing, in Zhejiang, to escape detection.
Hitler announced he would rejoin on the condition that he would replace Drexler as party chairman, and that the party headquarters would remain in Munich. The committee agreed, and he rejoined the party on 26 July as member 3,680. Hitler continued to face some opposition within the NSDAP: Opponents of Hitler in the leadership had Hermann Esser expelled from the party, and they printed 3,000 copies of a pamphlet attacking Hitler as a traitor to the party.
Hitler spoke to several packed houses and defended himself and Esser, to thunderous applause. His strategy proved successful, and at a special party congress on 29 July, he was granted absolute powers as party chairman, replacing Drexler, by a vote of 533 to 1
After the assassination of Milorad Drašković, the Yugoslav Minister of the Interior, by a young communist named Alija Alijagić on 2 August 1921, the CPY was declared illegal under the Yugoslav State Security Act of 1921.
Shortly after Philip's birth, his maternal grandfather Prince Louis of Battenberg, then known as Louis Mountbatten, Marquess of Milford Haven, died in London. Louis was a naturalized British subject who, after a career in the Royal Navy, had renounced his German titles and adopted the surname Mountbatten—an Anglicised version of Battenberg—during the First World War, owing to anti-German sentiment in Britain. After visiting London for his grandfather's memorial service, Philip and his mother returned to Greece, where Prince Andrew had remained to command a Greek Army division embroiled in the Greco-Turkish War.