What are Liam O'Flaherty's reasons for writing "Sniper"? Why exactly did he? When he was in the war was he a sniper?how old was he when he joined...

“The Sniper,” a story about the Irish civil war, was Liam O’Flaherty’s first published piece of fiction."  

Liam O'Flaherty was 19 years old when he joined the Irish Guards of the British army.  The author fought in World War I, receiving a medical discharge in 1917, after experiencing shellshock.

In the 1920s, the author became very involved with Irish politics.   He became a soldier once again, this time,  for the Irish Republican Army.  He took part in The Four Courts Incident. 

"In April 1922, Republican forces occupied Dublin’s justice buildings, the Four Courts. They came under siege from the Free State forces. For several days in June, the Free Staters bombarded the Four Courts. They retook the buildings and captured the enemy leader. Before their capture, however, the Republicans blew up the Four Courts."

He wrote  “The Sniper” during the Irish civil war.  He had first hand experience, as a soldier, although there is no mention that he was a sniper.   

The story is a sad commentary about the senselessness of war.  As the sniper shoots an enemy soldier,he discovers that he has killed his brother.  This story is an expression of how Irish society was fractured by the civil war.