In London, Queen Elizabeth observied a two minute silence before laying a wreath at the Cenotaph war memorial.
President McAleese attended an ecumenical service of remembrance and reconciliation at St Patrick's Cathedral in Dublin this afternoon.
In Belfast, Lord Mayor Martin Morgan of the SDLP laid a wreath at a service at the Cenotaph at City Hall.
Wreaths were also laid by the North's Security Minister Jane Kennedy on behalf of the British government and the Chief Constable Hugh Orde for the PSNI.
