a top-secret security operation was launched to protect charles from a feared terror attack by welsh nationalists at the caernarfon castle ceremony .
the eyes of the nation were on the heir to the throne for the historic event on july 1 , 1969 , but behind the scenes , prime minister harold wilson was convinced terrorists campaigning for welsh independence would target charles .
the targets of the operation were members of the nationalist groups movement for the defence of wales and the free wales army -lrb- fwa -rrb- .