Irish War of Independence 1921

Harold (seated in centre with moustache) in 1921

During the Irish War of Independence IRA activists such as the group below, started attacking British institutions across Ireland.

The situation became so serious that the British Government recruited a special militia force to try and suppress the rebels. This force was nicknamed the Black and Tans because of their mixture of police and army uniform (pictured below). They were recruited mainly from soldiers returning from the Great War. They were frequently violent and cruel in their dealings with the Irish civilian population and were universally despised.

In particular the IRA targeted the Coast Guard Stations which had been built around the whole Irish coast in Victorian times. These were often remote houses manned by retired sailors from the Royal Navy and therefore very vulnerable. In June 1920 the 8th Battalion Royal Marines was formed to go to Ireland specifically to defend these Coast Guard Stations. 

On Thursday 27 May 1920 a conference had taken place in the First Sea Lord's room at the Admiralty in response to representations from the C-in-C Western Approaches "that armed revolutionaries were attacking and burning Coastguard Stations (in Ireland) and ... civil and military authorities were incapable of protecting those stations." 
Orders were consequently given for 800 Marines to be sent to Ireland. Each Division plus the RMA had to send 195 officers and men, with "as many Old Soldiers as possible ... to be included." HMS Valiant and HMS Warspite were detailed as troopships and the newly formed battalion was ordered to concentrate on Plymouth.
At 4.00 pm on 3 June, 843 officers and men embarked. They arrived at Queenstown the following morning. On 18 June the Adjutant-General of the Royal Marines warned that units arriving in Ireland should be prepared for their ship to be fired upon and their train to be ambushed.
Harold Ozanne joined this Battalion in  June 1921 and returned to England in February 1922.
An idea of the extent of the violence can be gained from the following newspaper report: