Władysław's brother, John II Casimir, commanded one of the regiments in the relief army. Another notable commander was the Field Crown Hetman, Marcin Kazanowski. King Władysław IV, a great supporter of the modernization of the Commonwealth army, proved to be a good tactician, and his innovations in the use of artillery and fortifications based on Western ideas greatly contributed to the eventual Polish–Lithuanian success. He had replaced the old arquebusiers with musketeers, and standardized the Commonwealth artillery (introducing 3- to 6-pounder regimental guns), both to great effect.