The Howth gun running involved the delivery of 900 Mauser rifles to the Irish Volunteers at Howth harbour in Ireland on 26 July 1914. The unloading of guns from a private yacht during daylight hours attracted a crowd, and the authorities ordered police and military intervention. The Volunteers successfully evaded the security forces. As the King's Own Scottish Borderers returned to barracks, they were accosted by civilians at Bachelors Walk, who threw stones and exchanged insults with the regulars. The soldiers shot into the unarmed crowd and bayoneted one man, resulting in the deaths of four civilians and wounding of 38.
According to Darrell Figgis, the plan was first conceived in April 1914, in response to the Curragh incident on 20 March. Many Irish people believed that the British Army could not be relied on to enforce Home Rule when it was enacted, and many Irish Volunteers also felt that availability of arms would aid recruitment. At a lunch attended by Alice Stopford Green, Sir Roger Casement, Figgis and Eoin MacNeill, it was decided that Figgis would contact Michael O'Rahilly to raise funds to buy arms.
He was unsuccessful and the group was dismayed to learn of the Larne gun-running of the Ulster Volunteers (UVF). Senior Irish Volunteer Patrick Pearse had commented that: "the only thing more ridiculous than an Ulsterman with a rifle is a Nationalist without one". Casement asked Alice Green for a loan to be repaid when the volunteers bought their rifles. Casement, Figgis and Erskine Childers visited the London agent of a Belgian arms dealer. They eventually closed with a dealer in Hamburg, introduced to them by O'Rahilly, and settled on a sale of 1,500 rifles.