Arma Angelus

Arma Angelus was a metalcore band from Chicago. The band started in 1998 and broke up in 2002. The members of the band were Peter Wentz (singer, now plays bass guitar in Fall Out Boy), Tim McIlrath (played bass guitar, now lead singer of Rise Against), Jay Jancetic (played guitar, now plays guitar for the Chicago band Holy Roman Empire), Daniel Binaei (played guitar), Adam Bishop (played guitar, now an English teacher at San Dieguito High School Academy in Encinitas, California), and Timothy Miller (played the drums).
After Tim quit to start a new band called Rise Against, he was replaced in 1999 by Christopher Gutierrez. Gutierrez is now a touring author and spoken word artist. He was replaced as the bass guitar player for one tour by Joseph Trohman (now plays guitar in the band Fall Out Boy). Trohman was not a good fit for the band in terms of knowing about the music style and in terms of stage presence. He was replaced mid-tour when the band flew Chris Gutierrez out to New York for the final half of their tour, including a stop at CBGB's. 
In the last Arma Angelus concert, Patrick Stump played drums, Pete Wentz sang, Joe Trohman played guitar along with Adam Bishop, and Christopher Gutierrez on bass.