LONDON (AFP) - Britain will eventually be proud of its role in the Afghanistan war but it could be another decade before its gains are realised, the head of Britains armed forces said in an interview published in Thursdays Times. General Sir David Richards, the chief of the defence staff, admitted tactical mistakes had been made but that he had every expectation history would judge the war positively. At the end of the day, we wont know (if it has succeeded) until 2018, '19, '20, he told the British newspaper. I have every expectation that we will all agree in ten years time that this was a necessary war and weve come out of it with our heads held high, he added. Richards admitted last month that public support for the Afghanistan campaign was waning and that proponents of the war were losing the battle of perceptions among the British public. Public enthusiasm has been sapped by a steadily rising death toll among British soldiers, reports of troop and equipment shortages and U-turns in military tactics. Richards said he was the first to concede that mistakes had been made but pointed out that no terrorist attack had been launched out of Afghanistan since the campaign began 10 years ago. The general conceded that policymakers and military leaders were guilty of neglecting Afghanistan during the parallel campaign launched in Iraq in 2003, but added that strategy had been correct since US President Barack Obamas 2009 troop surge. Britain will withdraw 500 troops from Afghanistan by the end of next year, leaving 9,000 in the country. Some 389 British troops have been killed since US-led operations in Afghanistan began in October 2001. Of these, at least 344 were killed in combat. Prime Minister David Cameron has stressed that Britains commitment to Afghanistan would endure after the last Nato combat troops leave the country at the end of 2014.