This was blend of George Calvert’s, the First Baron of Baltimore, coat of arms from his fraternal and maternal side. On the Calvert side, the black and gold design was granted to George Calvert as a reward for his storming a fortification during a battle (the vertical bars approximate the bars of the palisade). The red and white design is the coat of arms of the Crossland family, the family of Calvert’s mother, and features a cross bottony. Since George Calvert’s mother was an heiress, he was entitled to use both coats of arms in his banner.
A side note on the notable buds of the cross bottony represents the Christian Trinity.
