“21 Guns”, the second single off 21st Century Breakdown, is a power ballad that questions war and shows a narrator looking for peace. When taken on its own out of the 21st Century Breakdown story-arc, the song’s lyrics can be interpreted as anti-war, however, when applied to the story of Christian and Gloria, its meaning is far less global; instead, they’re referring to their relationship and all its conflicts.

The name “21 Guns” comes from the 21 Gun Salute, the customary gun salutes that are performed by the firing of cannons or artillery as a military honor.

Billie told Q Magazine:

It brings up 21st Century Breakdown in a lot of ways, and the 21-gun salute for someone that’s fallen, but done in an arena rock ‘n’ roll sort of way.

The song reached No. 3 on the Alternative Songs chart and No. 17 on the Hot Mainstream Rock Tracks chart. It also reached #7 on the Billboard Pop Songs chart. It was nominated for a Grammy for Best Rock Performance by a Duo/Group with Vocals and Best Rock Song in 2010.