A former defence secretary has said he cannot think of a "nastier" military campaign to be involved in than that being waged in Afghanistan.
Conservative peer Lord King of Bridgwater said however that the objectives had "effectively been achieved" and he supported the gradual withdrawal from the country.
The government has promised to bring the majority of UK troops home from Afghanistan by the end of 2014.
During a debate on the contribution of the armed forces in to the UK, Lord King said it was important that people understand what the mission in Afghanistan is for.
"There is a very heavy responsibility on the government, on leaders in all parties - it is a bi-partisan situation inherited from the previous government, carried on by the present government - to make sure people understand why they are serving in Afghanistan and what the objective is."
The peer also called for more continuity at the Ministry of Defence with less turnover of secretaries of state.
"No business would run with the leader, the boss leaving every year," he told peers.
The debate in the Lords was tabled by government defence spokesman Lord Astor of Hever in the week before Remembrance Sunday on 11 November.
Lord Astor told peers the mission in Afghanistan remained the first priority for the armed forces.
He said Afghan forces were increasingly "taking the lead" in operations there, allowing the UK to reduce its troop levels.
The minister said the UK would continue to support Afghanistan after 2014, through the non-combat mission to be set up by Nato.