The military clash known as the Defence of Drogheda took place on the Wild Space planet Drogheda in the year 13,649 BBY. It was a component of the fourth of the Alsakan Conflicts, a series of wars fought between the planet Coruscant, Alsakan and their associated allies.
Jason Fry and Paul R. Urquhart made reference to the Defence of Drogheda in their book, The Essential Guide to Warfare, which was released in 2012.