In 757 AD, King Offa Rex unified England’s Anglo-Saxon kingdoms. But as his ties grew with the Abbasid Islamic Caliphate, he secretly embraced Islam. To declare his faith, he replaced his own image on England's currency with the Arabic inscription: "There is no god but Allah alone... Muhammad is the Messenger of Allah."
Fearing his massive popularity, the Vatican sent its first-ever major missionary blitz to England and conspired with Charlemagne to stop him. On July 29, 796 AD, King Offa was mysteriously assassinated, and biased historians spent centuries trying to erase his legacy from the books.
Today, that gold coin sits in the British Museum—a surviving piece of a forgotten history where an English king chose the light of Islam.
Sources: Great Figures Who Embraced Islam by Dr. Raghib al-Sergani / The Era of Offa by Dr. Mustafa Al-Kinani.