Having attended the Royal Naval College, Dartmouth, Haddacks joined the Royal Navy in 1964 and specialised in navigation. He commanded successively the frigates HMS "Cleopatra" and HMS "Naiad". He went on to be assistant director of Navy Plans in the Ministry of Defence and was later given command of the assault ship HMS "Intrepid". He became Senior Naval Officer Middle East and commander of UK maritime forces during Operation Desert Shield in 1990, Assistant Chief of Staff Policy and Requirements Division at SHAPE in 1994 and UK Military Representative to NATO in 1997. He was appointed Director of the International Military Staff at NATO in 2001 and retired in 2004.