“It has Civil War roots you know.”
No, not at all.
It is much older than that. They are the heraldic colors of the Calvert and Crossland families, former who were granted proprietorship here.
Suggest you read this .
http://www.sos.state.md.us/Services/FlagHistory.aspx
During the war, Maryland-born Confederate soldiers used both the red-and-white colors and the cross bottony design from the Crossland quadrants of the Calvert coat of arms as a unique way of identifying their place of birth. Pins in the cross bottony shape were worn on uniforms, and the headquarters flag of the Maryland-born Confederate general Bradley T. Johnson was a red cross bottony on a white field.
By the end of the Civil War, therefore, both the yellow-and-black Calvert arms and the red-and-white colors and bottony cross design of the Crossland arms were clearly identified with Maryland, although they represented opposing sides in the conflict. As officers and soldiers returned home after the war to resume their peacetime occupations, the greatest challenge facing the country was reconciliation. Nowhere was the problem more serious than in deeply divided Maryland, where veterans who had fought under the red-and-white secession colors” had to be reintegrated into a state that had remained true to the Union.
As the slow process of reconciliation took place in post-Civil War Maryland, a new symbol emerged. A flag incorporating alternating quadrants of the Calvert and Crossland colors began appearing at public events. While the design derived directly from the seventeenth-century Calvert family coat of arms, for Marylanders of the 1880s the new banner must have conveyed a powerful message. The passage of time had gradually diminished the passions of former Rebels and Yankees, permitting them to work together once again. Now the colors they had fought under had come together as well, symbolically representing through this new flag the reunion of all the state’s citizens.