The PM lauds military service personnel as a national event to recognise the work of the Armed Forces takes place in Liverpool.
The Prime Minister led the tributes and thanks, saying: "It is wonderful that we mark the tremendous job that our Armed Forces do for us here at home and across the world, helping to keep us safe."
Speaking at one of the military events in Liverpool, Theresa May added: They do a fantastic job for us and we should be grateful to them all."
She also hailed the role of UK troops in dealing with terrorism at home and abroad.
Defence Secretary Sir Michael Fallon, who also attended the national event on the city's waterfront, said: "There are some 10,000 servicemen and women who are working for us around the globe on operations or in our bases.
"They have been helping to deal with Daesh terrorism, they have been helping to rescue migrants in the Mediterranean, they have been on NATO deployments, they have been peacekeeping in South Sudan.
"All of that keeps us safer here at home."
Sir Michael went on to praise the reaction of the Army following the terror attack at the Manchester Arena, in which 22 people lost their lives.
Nearly 1,000 armed troops were deployed within 12 hours of the bombing - freeing up armed police to do more patrolling.