The hammer and the anvil
From A Wiki of Ice and Fire
Regarding the Battle of the Redgrass Field during the Blackfyre Rebellion, singers sing of the hammer and the anvil. Prince Baelor Targaryen (the hammer) led Dornish spearmen against the rear of Daemon Blackfyre's rebel army and crushed it against the shield wall of Prince Maekar Targaryen (the anvil). However, Ser Eustace Osgrey felt the singers left out much from what actually happened.