Background
He was born in Buttevant, County Cork and joined the Irish Defence Forces at age 17 in 1939.
He was born in Buttevant, County Cork and joined the Irish Defence Forces at age 17 in 1939.
He graduated from the Military College at Curragh Camp, County Kildare.
Early Military He is most famous for being the Commanding Officer of the United Nations Interim Force in Lebanon from 1981 to 1986. A needed neutral United Nations Peacekeeping military command leadership during the Lebanese Civil War that hastened the various military, peacekeeping, and general tasks which lead to the successful environment of the Multiforce. O'Callaghan was a County Cork native who had the unique distinction of holding the 2 most important United Nations appointments in the Middle East and arguably the world during a particularly tumultuous period in the 1970s and 80s, when he was the Force Commander of the United Nations Interim Force in Lebanon (UNIFIL) from February 1981 to May 1986 and the United Nations Truce Supervision Organisation (UNTSO) from April 1978 to June 1979 and again from May 1986 to June 1987, commanding multinational troops in Syria, Lebanon, Israel, Egypt and Jordan.
In an interview in April 1982 with American magazine "People", with UNIFIL having suffered 145 combat casualties in its previous 4 years, 35 of them fatalities, he said: Other individuals quoting on Lieutenant General O'Callaghan: Lt Gen William Callaghan Sword Irish cadets in training compete for an award named in his honour. The “Lt Gen William Callaghan Sword” is awarded to the cadet who displays the best tactical ability. Honours and Irish National Honors Foreign National Honors = French Honors = Arab Honors.