Soon afterwards, local tribes, including the Grebo and the Kru, attacked the State of Maryland. Unable to defend itself, Maryland asked Liberia, its more powerful neighbor, for help. President Roberts sent military help, and an alliance of Marylanders and Liberian militia troops stopped the local tribesmen. However, it was now clear that the Republic of Maryland could not survive on its own, and 18 March 1857 Maryland was added by Liberia, and became known as Maryland County.