Furious that Parliament continued to countenance Charles as King, troops of the New Model Army marched on Parliament and purged the House of Commons in an act later known as "Pride's Purge" after the commanding officer of the operation. On Wednesday, 6 December 1648, Colonel Thomas Pride's Regiment of Foot took up position on the stairs leading to the House, while Nathaniel Rich's Regiment of Horse provided backup. Pride himself stood at the top of the stairs. As Members of Parliament (MPs) arrived, he checked them against the list provided to him. Troops arrested 45 MPs and kept 146 out of parliament.