Thomas Moore - Avenging and Bright

Avenging and bright fall the swift sword of Erin
On him who the brave sons of Usna betray'd! --
For every fond eye he hath waken'd a tear in
A drop from his heart-wounds shall weep o'er her blade.

By the red cloud that hung over Conor's dark dwelling,
When Ulad's three champions lay sleeping in gore --
By the billows of war, which so often, high swelling,,
Have wafted these heroes to victory's shore --

We swear to avenge them! -- no joy shall be tasted,
The harp shall be silent, the maiden unwed,
Our halls shall be mute, and our fields shall lie wasted,
Till vengeance is wreak'd on the murderer's head.

Yes, monarch! though sweet are our home recollections,
Though sweet are the tears that from tenderness fall;
Though sweet are our friendships, our hopes, our affections,
Revenge on a tyrant is sweetest of all!

Thomas Moore

http://www.poemhunter.com/poem/avenging-and-bright/