Queen Marcia was the mythical third female ruler and a regent of the Britons, as recounted by Geoffrey of Monmouth. She is presented by Geoffrey as "one of the most illustrious and praiseworthy of women in early British history".
Queen Marcia ruled Britain for about five years after Guithelin's death because their son was just seven years old at the time.
Geoffrey says that Queen Marcia was a learned woman who codified the Marcian Laws, the Lex Martiana. King Alfred the Great was later to translate the code into Old English as the basis of Mercian Laws, believing them to have been named after the much later Saxon kingdom of Mercia.
- Monmouth, G. (Galfredus Monumetensis). History of the Kings of Britain. p. 101.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
- Barefield, Laura D., Gender and History in Medieval English Romance and Chronicle, Peter Lang, New York, 2003, p.27.
- Cooper, B. "History of the Early British Kings". Retrieved 2011-02-07.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
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