They were used as defences against the attack of the French and later the Americans, especially in the War of 1812. They are tall, square structures, often built on top of a hill. Of course, my local community was named after a Blockhouse, a recently a Blockhouse has been restored in the Town of Lunenburg where I work. I play a little chess on the chess servers. I'm also busy reviving the Lunenburg Chess Club which meets every Tuesday from 6 to 9 pm in the Mug and Anchor Pub in Mahone Bay, Lunenburg County, Nova Scotia.
Prize fund depends on entries.
Also interested in your recommendations on good books on the topic of Anti-Sicilians. See the Nova Scotia Chess Links for some of my favorite links.