Prime Minister Gordon Brown did not understand the significance of Britain's military campaign in Afghanistan until a few months ago, a former Army chief-turned-Tory adviser said today.
But General Sir Richard Dannatt said he was now "encouraged" that the Government was moving in the right direction on troop numbers, after Mr Brown announced reinforcements bringing the UK deployment to around 10,000, including special forces.
His comments came a day after the death of the 100th British soldier in Afghanistan this year, as Defence Secretary Bob Ainsworth paid an unannounced visit to troops in Helmand province.
Mr Ainsworth said his thoughts were with the family and friends of the dead soldier and added that the mission in Afghanistan was vital to national security.
He told Sky News: "Here in Afghanistan there is a sense of very real progress in this mission and that we are putting things where they need to be."
US Defence Secretary Robert Gates also flew into Afghanistan today on a separate unannounced visit.
Unconfirmed reports have suggested that Gen Dannatt clashed privately with Mr Brown earlier this year over the then Chief of General Staff's demand for 2,000 more troops to be sent to Afghanistan.
Today he said his dealings with the PM were "mixed".
But he told the BBC Radio 4 Today programme: "In my last three encounters with him, at the end of July and the beginning of August after I got back from my last trip to Afghanistan, I felt he was beginning to get it.
"It was late in the day that he was beginning to get it but I think he began to understand the significance and the importance of what we were doing in Afghanistan.
"And I am encouraged that we appear to be making progress in that direction now."
He defended his decision to take up a post advising the Tories after retiring from the military in August, insisting he was motivated by "the chance to give straight and above-the-radar advice to what will probably be the incoming government".
Gen Dannatt's successor as Army chief, General Sir David Richards, said today that the 100th fatality of 2009 "hardens our determination to succeed" in Afghanistan.
Commenting after the grim milestone was announced last night, Gen Richards urged the public not to judge the campaign by casualties alone.
The serviceman, from 1st Battalion The Royal Anglian Regiment, died from small arms fire yesterday in the Nad-e Ali area, central Helmand Province, and his family has been informed.
His death brings the total number of British service personnel who have died since the start of operations in Afghanistan in 2001 to 237.
This year has been the bloodiest for British forces since the Falklands War in 1982, and follows 39 British deaths in the Afghan conflict in 2006, 42 in 2007 and 51 in 2008.
The Prime Minister also paid tribute to the soldier, saying: "We will never forget those who have died fighting for our country and we must also honour their memory. That means staying the course, doing what is right for Britain, and seeing this mission through."
Chief of the Defence Staff Air Chief Marshal Sir Jock Stirrup admitted 2009 has been a "particularly challenging year" but said the sacrifices "have brought security to more of the population of Helmand, and have helped the Afghan National Army to develop its own capabilities to protect the people".
He said: "There is still much to do, and there will be difficult days ahead, but our Armed Forces are making a real difference, and are building the basis for enduring success in Afghanistan."
Mr Ainsworth is due to meet British troops and commanders as well as Afghan officials over the next few days.
His visit comes as Britain and America continue to press Nato allies to send more troops to Afghanistan, following US President Barack Obama's announcement of a 30,000-strong troop surge and Mr Brown's deployment of an additional 500 British soldiers.
Nato Secretary-General Anders Fogh Rasmussen has said non-US members of the alliance will send at least 5,000 reinforcements.
But, apart from a promise of 600 troops from Poland, there have been no other immediate offers of troops.