'En-e-ry the eighth is five syllables and so is Sargon of Akkad, so it works fine. You just have to sing 'Sargon of' as if it were one word. Sargonof. However invaded has one syllable too many (compared to married).
Why are you writing a song about an Akkadian ruler from the 24th to 23rd centuries BC? I had to look him up I admit so if it's meant to be educational it's worked on me. Although I haven't bothered to learn anything about him.
I went with "Everyone was Akkadian/ Except for Ebla and Elam/ And everyone was Akkadian/ Sargon of Akkad I am"
I decided to write it because fishing hadn't really gotten started and I was in a state of unworldly boredom.
Many classic pop hits have started off in similar circumstances I'm sure. It will be a pleasure to see you at the top of the hit parade, even if only as a one hit wonder. Just make sure you get your royalties in years to come.