D Day - Operation overlord
On the 6th June 1944 the allies launched a combined naval, air and land assault on Nazi-occupied France. This was codenamed "overlord" but is better known as the D-Day landings.
To remember that D-Day was called operation "overlord" reflect on the following mnemonic.
The day (D-Day) that it happened we all got on our knees and prayed let this be "OVER LORD."(operation overlord).