'Flight of the Earls') and the aforementioned Plantation of Ulster in 1609. 1627 Hispano-Irish proposal In Europe, prior to the 18th and 19th centuries, republics were in a minority and monarchy was the norm, with few long-lasting republics of note at time, such as the fully-fledged Dutch Republic and the Republic of Venice, as well as the Old Swiss Confederacy and the Polish–Lithuanian Commonwealth, which had republican aspects. However, as noted by Cardinal Tomás Ó Fiaich, the first ever document proposing a republic of Ireland independent from connections to England dates from 1627. Summaries of these plans are held in the Archives générales du Royaume in Belgium and were made familiar to Irish historians by the work of Fr. Brendan Jennings, a Franciscan historian, with his work Wild Geese in Spanish Flanders, 1582-1700 (1964). This early republican spirit was not ecumenical and was formed by exiled Irish Catholic Gaels with the support of Habsburg Spain as part of the Irish military diaspora who had fled into Spanish service in the aftermath of the Flight of the Earls during the Thirty Years' War. This was in the context of the break-down of the Spanish match and the onset of the Anglo-Spanish War of 1625–1630. Proposals were made at Madrid, with the involvement of Archbishop Florence Conry and Owen Roe O'Neill, for the Irish Regiment in the Spanish Netherlands then in the service of the Infanta Isabella Clara Eugenia, to invade and reconquer the English-controlled Kingdom of Ireland and set up an Irish government loosely aligned with the Habsburg Empire. One of the main problems was that within the leadership of the Hispano-Irish diaspora, there were rivalries and factionalism between two primary contenders, Shane O'Neill and Hugh O'Donnell, over who should be the overall leader and thus have rights to an Irish throne if the project was a success. A third option was to resolve the conflict between the two factions before an invasion by making them family, with a marriage proposed between Hugh O'Donnell's sister Mary Stuart O'Donnell and Shane O'Neill, but this broke down. Ministers in Madrid, to Philip IV of Spain, instead drew up proposals on 27 December 1627 for a "Kingdom and Republic of Ireland" and that "the earls should be called Captains General of the said Republic and one could exercise his office on land and the other at sea." These proposals were approved by Philip IV