Breath of Fury attached to any creature that isn't your commander.
An opponent cannot block creatures you control.
Steps
Declare your commander and the creature with Breath of Fury attached as attackers.
We Ride at Dawn's second ability triggers, creating a 1/1 Mercenary creature token.
Deal combat damage using the creature that has Breath of Fury attached.
Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the Mercenary token, then causing you to untap all creatures you control and to get an additional combat phase after this one.