I pledge allegiance to the flag of the United States of America, and to the republic for which it stands, one nation under God, indivisible, with liberty, and justice for all.
You may be surprised to find out, we don't have an equivalent of this in the UK.
I can think of a nation that had something similar though. It went like this.
"I swear by God this sacred oath that to the Leader of the German empire and people, Adolf Hitler, supreme commander of the armed forces, I shall render unconditional obedience and that as a brave soldier I shall at all times be prepared to give my life for this oath."
The Wehrmacht Oath of Loyalty to Adolf Hitler, 2 August 1934