"Slug" Rees joined the New Zealand Division of the Royal Navy at HMS Philomel in February 1940 as a telegraphist for 'special instruction', after having served in the Canterbury Division of the Royal Naval Volunteer Reserve. In May of that year, he was seconded to the Royal Navy and, while there, he served in the Atlantic, Mediterranean and Pacific on the aircraft carrier HMS Victorious. During this time he was promoted to Temporary Sub Lieutenant and later was first lieutenant of the Landing Craft Tank 1149, part of the June 1944 invasion of France. Returning to New Zealand in late 1944, he spent the rest of his time in the service in the Navy Office, Wellington, before being discharged in September 1945.
- 1939-1945 Star (Miniature) - Miniature version of the 1939-1945 Star. Recognises service in the Second World War. It was usually awarded for six months service in special operational areas. Those whose service was shortened by death, injury or capture or who were awarded a decoration or mentioned in despatches also qualified for the medal. Those who served a day or more in specified battles or invasions also qualified for this award. The ribbon has three equal vertical stripes of dark blue (symbolising Navy and Merchant Navy), red (symbolising Army) and light blue (representing Air Force).
- Atlantic Star (Miniature) - Miniature version of the Atlantic Star. Awarded to personnel who served an additional 6 months in Home (United Kingdom), Atlantic or North Russian waters after first qualifying for the 1939-45 Star. The ribbon is water silk coloured blue, white and green. These colours symbolise service in the Atlantic Ocean, and in UK and North Russian waters.
- Africa Star (North Africa 1942-43 Clasp) (Miniature) - Miniture version of the Africa Star with a 'North Africa 1942-43' clasp. Awarded for service in North Africa between 10 June 1940 and 12 May 1943. The ribbon is pale buff in colour with a central vertical red stripe and narrower stripes, one dark blue and one light blue. The pale buff background symbolises the desert, the red stripe symbolises the Army, the dark blue stripe symbolises the Navy and Merchant Navy, while the light blue stripe symbolises the Air Force. New Zealand soldiers who were captured or killed in Greece or Crete in 1941 had qualified for this star before entering Greece. This was because they were based in Egypt on or after 10 June 1940, before being sent to Greece.
- Pacific Star (Miniature) - Miniature version of the Pacific Star. The Pacific Star was awarded for operational service in the Pacific between 8 December 1941 and 2 September 1945.It was also awarded for certain specified service in China and Malaya (8 December 1941 - 15 February 1942), Hong Kong (8 December 1941 - 25 December 1941) and Sumatra (8 December 1941- 23 March 1942). The Green stripes on the ribbon symbolise the jungle while the central yellow stripe symbolises the beach. The outer red stripes symbolise the Army while the dark blue stripe symbolises the Navy and Merchant Navy and the light blue stripe symbolises the Air Force.
- The Defence Medal (Miniature) - Miniature version of the Defence Medal. Awarded to British military and civilian personnel for a range of service in the United Kingdom, and to British, British Commonwealth and British Colonial personnel who served outside their home countries in a non-operational area or in an area subject to threat such as air attack. The centre of the ribbon is flame coloured, and the edges are green, symbols of the enemy attacks on Great Britain. Two black stripes represent the blackout in Great Britain.
- War Medal (Miniature) - Miniature version of the War Medal. Awarded across the British Commonwealth to all fulltime members of the Armed Force for 28 days service between 3 September 1939 and 2 September 1945 irrespective of where they were serving. On one side is an effigy of King George VI. On the reverse is a lion trampling on a dragon symbolising the Axis powers. The ribbon is the red, white and blue of the (British) Union Flag.
- New Zealand War Service Medal (Miniature) - Miniature version of the New Zealand War Service Medal. Awarded for 28 days' full time service or six months' part time service in any of the New Zealand Armed Forces, the New Zealand National Military Reserve or the Home Guard between 3 September 1939 and 2 September 1945. Eligible part time Home Guard Personnel must have completed their six months' part time service between 16 August 1940 and 1 January 1944 (the Home Guard was disbanded in December 1943). It was the first distinctively 'New Zealand' war service medal, which was emphasised by the use of the fern leaf motif on the suspender and the reverse of the medallion, and the national colours of black and white on the ribbon.