This is the counterfoil from a mobilisation order (which has also survived) sent by William Pearse (1881-1916) to Seán Thomas O'Kelly (1882-1966) on 21 April 1916.William Pearse was a sculptor and brother of Patrick Pearse, one of the leaders of the Easter Rising. William held the rank of captain on the headquarters staff of the Dublin Brigade of the Irish Volunteers. O'Kelly was a politician and later president of Ireland. In 1916 he was also a member of the Irish Volunteers and Irish Republican Brotherhood and served as aide-de-camp to Patrick Pearse during the Rising. The order was a personal order for O'Kelly, signed by 'Acting Chief of Staff' Willie Pearse, and was for the planned manoeuvres on Easter Sunday, 23 April. Unbeknownst to the rank and file, these manouevres were to be used as a cover for the beginning of the Easter Rising but were countermanded by Eoin MacNeill, chief of staff of the Irish Volunteers, when he became aware of the plans. The Rising then went ahead on 24 April with significantly reduced numbers. The counterfoil was to be signed and returned to William Pearse but never was.William Pearse was executed for his part in the Rising on 4 April. O'Kelly was arrested and imprisoned until December 1916.