Prince Harry has met Estonian troops taking part in a major Nato training exercise during his visit to the Baltic state.
The prince also met service personnel from the UK and the United States involved in operation Spring Storm.
He joked with an old roommate from his time in Afghanistan, and met Estonia's president, Toomas Hendrik Ilves.
He later travelled to Italy as part of three-day official visit, which has been organised by the Foreign Office.
Prince Harry, who has twice served in Afghanistan, spent more than two hours meeting the multi-national forces, near the southern Estonian town of Otepaa.
The prince spotted the "familiar face" of one the Estonian troops, Captain Tanel Tarlap, who he said had let him use his computer when they were in the same room in Afghanistan.
As the two men met for the first time in more than six years, the Estonian officer smiled and said: "So you could email your girlfriend."
Operation Spring Storm is the final exercise for Estonian conscripts after months of training.
Soldiers from the 1st Battalion the Duke of Lancaster's Regiment, who have worked alongside their Estonian counterparts in Afghanistan, were also taking part in the joint operation which ends next week.
The prince later issued a short statement saying it had been "fantastic" to meet the Estonian soldiers.
"The qualities the whole Estonian Army embodies are something the country can be immensely proud of," he said.
On Friday he paid tribute to Estonia's troops as he laid a wreath in memory of people who had died fighting for the country.
In the Italian leg of his visit, he will join commemorative events marking World War Two's Italian campaign, focusing on the 70th anniversary of the Battle of Monte Cassino.