Complex sentence: Rear Admiral Sir David James Martin (15 April 193310 August 1990) was a senior officer of the Royal Australian Navy and later Governor of New South Wales who later went on to establish Sir David Martin Foundation to assist young Australians in crisis.
Split into simpler sentences: Rear Admiral Sir David James Martin (15 April 1933--10 August 1990) was a senior officer of the Royal Australian Navy and later Governor of New South Wales. He also established the Sir David Martin Foundation to assist young Australians in crisis.