UK unofficial anthem

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Listen to this UK unofficial anthem (originating from a poem by James Thomson and set to music by Thomas Arne in 1740. It is strongly associated with the Royal Navy, but also used by the British Army.) and find the missing words.

When Britain fi-i-irst, at heaven's command,
Aro-o-o-ose from out the a-a-a-zure main,
Arose, arose from ou-ou-ou-out the a-zure main,
This was the charter, the charter of the land,
And guardian a-a-angels sang this strain:

", ! the :
" , , shall be ."