City and Colour is the solo acoustic project of Dallas Green, singer and guitarist for the Canadian post-hardcore band Alexisonfire. While the band developed a strong following from its 2004 album, “Watch Out!” Green began selling copies of his first solo album, “Sometimes,” shortly thereafter and supported it with sold-out tours through North America and the United Kingdom. Followed were two more successful albums: “Bring Me Your Love” and “Little Hell.” Alexisonfire announced its breakup in 2011, with Green wanting to focus on City and Colour. It performs at the National on Thursday, May 31, at 8 p.m. $25. 612-1900.