He was promoted to brigadier, unusually having never held the rank of colonel, and took command of 20th Armoured Brigade in Germany before becoming I Corps chief of staff.

[1][5] In 1969 he was posted to Cyprus for a two-year tour, and served in Northern Ireland during The Troubles,[1] before attending the Staff College, Camberley.

[6][7] After serving in a staff position at the Ministry of Defence (MoD), Walker was promoted to major at the end of 1976,[8] and rejoined the 1st Battalion, to become a company commander, based in Tidworth, Wiltshire.

[16][17] On 8 December 1994, Walker was appointed commander of NATO's Allied Rapid Reaction Corps, which had its headquarters in Rheindahlen, Germany, and was promoted to acting lieutenant general.

There, he became the first commander of the land component of the NATO-led Implementation Force (IFOR), until his return to the UK in November 1996.

[1] His IFOR command in Bosnia was indirectly criticised by Richard Holbrooke for his refusal to use his authority to also perform nonmilitary implementation tasks, including arresting indicted war criminals: Based on Shalikashvili's statement at White House meetings, Christopher and I had assumed that the IFOR commander would use his authority to do substantially more than he was obligated to do.

Smith and his British deputy, General Michael Walker, made clear that they intended to take a minimalist approach to all aspects of implementation other than force protection.

Smith signalled this in his first extensive public statement to the Bosnian people, during a live call-in program on Pale Television – an odd choice for his first local media appearance.

[24] In recognition of his service with IFOR between 1995 and 1996, Walker was awarded the American Legion of Merit (Degree of Commander), and granted unrestricted permission to wear the decoration, in May 1997.

[31] His comments were rejected by a spokesman for the National Union of Journalists, who retaliated "When generals turn around and start blaming reporters for their own mistakes, it is a sign they aren't doing their own jobs properly".

However, the MoD explained that speculation in the press about the timing and movement of military units can put people in danger and editors were "urged to consider the difficulties reports could cause to troops on the ground.

[33] In an interview with the BBC in October 2005, Walker suggested that the army's recruitment had been adversely affected by the Iraq War.

[34] In the same month, he gave an interview for The Sunday Times, in which he said that soldiers' morale had been damaged by the unpopularity of the war among the British public.

[13] In September 2006, Walker was appointed Governor of the Royal Hospital Chelsea, holding the post until February 2011 when he resigned suddenly.