The atavistic religious warfare currently ravaging Northern Ireland is well-nigh incomprehensible to foreign observers uninitiated in the contorted sectarian politics of Ulster, but this lucid and toughminded book by the London Times Insight Team goes a long way toward clarifying the pressures and policies behind the present guerrilla violence. It begins with an account of the traumatic failure of the IRA's last fruitless campaign against the North (1956-1962) and its aftermath which led to the leadership's turning away from traditional IRA policies of terrorism to espouse a new ""political"" line which led to the birth of the Catholic Civil Rights Movement in 1967. How this essentially middle-class reformist movement was persecuted into revolutionary action by the Stormont government backed by the Orange lodges and fueled by the incendiary rhetoric of Ian Paisley is the story of this book. The Insight reporters place the burden squarely on the shoulders of the Protestant militants -- they subverted the paltry reform efforts of ex-Prime Minister Terence O'Neill who represented Ulster's last hope of saving itself from bloodletting. After O'Neill the escalation of Protestant, then IRA violence, the schism within IRA ranks (precipitated by the Officials' reluctance to arm the terrified, embattled Catholics of Bogside), the sinister rise of the Protest Ulster Volunteers, and the government's sweeping internment policies, followed with the inexorable logic of an ancient scenario. Heath's government is charged with pusillanimous equivocation and failure to support first O'Neill then Chichester-Clark, and recent attempts to whitewash brutalities in the internment camps are presented with unsparing candor including pointed parallels with French actions in Algeria. Unfortunately the book stops short of most recent developments: British suspension of the Stormont government in favor of direct rule from Westminster, and recent signs of Catholic disaffection with the indiscriminate terrorism of the Provisionals. Nonetheless this is an invaluable background digest of the bewildering escalation of events in the little country which threatens to become England's Vietnam.