Declan I was declared joint Emperor by Parliament on 19 December 2010, after forces loyal to him took control of the Austenasian vassal states in Carshalton in opposition to Esmond III. He became sole Emperor in September 2011, and reigned until his abdication in January 2013.

The reign of Declan I has a controversial legacy. He did not visit Austenasia during his reign as Emperor, instead ruling via the internet from his home kingdom of Wilcsland (of which many suspect he saw Austenasia as little more than a vassal), and intentionally encouraged an absolutist view of his reign. However, his remote rule – communicating with Parliament via the Internet – laid much of the logistical groundwork for an online government, enabling the Empire to expand soon after his reign to administer claims from around the world.

During his reign, the Emperor became the undisputed leader of the nation. The soft power held by the Monarch that had in many cases been unofficially exercised by Esmond III became written into law under Declan with the promulgation of the current Constitution. After his abdication in Austenasia, Declan remained ruler of some of the local nations in Carshalton until June 2013, when he was deposed and new vassal monarchs appointed by Jonathan I.