evidence: The Provisional Irish Republican Army, or IRA, was the best known of the conflict's paramilitary groups. In their version, IRA combatants were soldiers fighting to expel the British from the island. [...] Republican and loyalist paramilitary groups alike tossed bombs into busy pubs, assassinated innocent people and committed appalling acts of kidnap and murder. The police and army killed civilians, too. [...] More than half of former paramilitaries surveyed in 2010 reported symptoms of post-traumatic stress disorder, a condition that can manifest in years of flashbacks and panic attacks and can intensify with age. Witnessing violence to another person — even an enemy — can be more distressing in the long term than being injured oneself, according to a study cited by the war correspondent Sebastian Junger.