Excerpts from Books and Wikipedia
"British troops had been deployed in Northern Ireland in 1969 to quell sectarian violence and were initially welcomed by the Catholic, republican population as protectors, but relations had soured. . . . There was worldwide condemnation of British actions, and an enraged mob burned down the British Embassy in Dublin. Sectarian hostilities were hardened, the IRA received a major boost in support, and the scene was set for political deadlock and terrorist atrocities that persisted for decades." [Furtado: 1001 Days]