The Age of Aggression

This song is known to be sung by almost every bard in Skyrim. It's a pro-Imperial song that is typically sung in Imperial controlled cities. The song is normally sang in inns that are in control of the Imperial Legion.

The Age of Aggression and The Age of Oppression are variants of one song. It isn't known which of the two was written first but the tune, with loyalty appropriate lyrics, is quite popular on both sides of the war.

Lyrics
We drink to our youth, to days come and gone. For the age of aggression is just about done. We'll drive out the Stormcloaks and restore what we own. With our blood and our steel we'll take back our home. ''Down with Ulfric! The killer of kings!'' On the day of your death we'll drink and we'll sing. We're the children of Skyrim, and we fight all our lives. And when Sovngarde beckons, every one of us dies! But this land is ours and we'll see it wiped clean. Of the scourge that has sullied our hopes and our dreams!

Trivia

 * Ulfric Stormcloak can rarely be heard mumbling these lyrics when he is sleeping. This is assumed to be a joke by Bethesda.