The Fenian movement (Irish Republican Brotherhood) was a secret society that attempted to achieve Irish independence through insurrection, such as the Easter Rising in 1916, when Britain was involved in World War One.
Citation:
Editors. "Fenians arrested for planning uprising".
The Literary Encyclopedia. First published 01 February 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=5088, accessed 23 May 2013.]