The team began play in 2009 as the Milwaukee Iron, and competed in af2, the AFL's developmental league. They joined the AFL after the league's restructuring in 2010. On January 27, 2011, the team officially changed its name to the Mustangs, after an older team that had played in the AFL from 1994 to 2001. Their final head coach was Bob Landsee. The Mustangs were dormant for the 2013 season. In October 2013, the rights to the franchise were sold to Terry Emmert, who subsequently started the Portland Thunder in Portland, Oregon.
Milwaukee IronThe Milwaukee Iron were announced as an af2 expansion team in March 2008 when the team's ownership group announced a three-year lease agreement to play at the Bradley Center beginning with the 2009 season. The announcement came the day before the Milwaukee Bonecrushers kicked off play in the Continental Indoor Football League at Milwaukee's US Cellular Arena.
Milwaukee had been without an arena football team since the Milwaukee Mustangs of the Arena Football League folded in 2001 after not being allowed to play at the Bradley Center.
The Iron played its first game on Thursday, March 12, 2009, a 60-0 exhibition shutout of the New Zealand Overstayers at the Bradley Center. They opened the regular season on Friday, March 27, 2009 when they played host to the Iowa Barnstormers. The Iron lost 60-38.
The Iron entered the Arena Football League in 2010. The team finished the year 11-5 and won the Midwest Division.
Milwaukee MustangsThe team changed its name to the Mustangs on January 27, 2011. The name "Mustangs" was chosen as it was the name of the original franchise that existed from 1994 to 2001. The team's dancers and New York City escorts were called the Fillies. The Mustangs were covered locally by WAUK (540 ESPN MILWAUKEE) and Time Warner Cable Sports 32.
On October 2, 2013 the AFL announced that an ownership group led by Portland businessman Terry W. Emmert has been approved by the AFL’s Board of Directors to purchase a majority of the Milwaukee Mustangs and relocate the team to Portland, Oregon. The team began regular season play as the Portland Thunder in 2014 at the Moda Center (20,636), home of the NBA’s Portland Trail Blazers