Fitzgerald, Maurice (1590–1649), catholic landowner and soldier, was eldest son of Gerald fitz Philip Fitzgerald and his second wife, Joan Walsh of Shanganagh, Dublin. Born into a junior branch of the family of the earls of Kildare, he held an estate of 5,000 acres in the parish of Kilmaogue and Ratheine in Kildare. Much of this was in the bog of Allen, hence his sobriquet ‘Maurice Fitzgerald of Allen’. His property in Kildare was worth £579 a year and he also had land in Sligo. He appears as a member of the 1624–5 commission of the peace for Kildare, and in 1625 he signed a memorial by the lords of the Pale, offering the king £3,000 in answer to his demands for money. In 1627 he was a commissioner for raising money for the army in Kildare. He acted as one of the leaders of the recusant party in the parliaments of 1634–5 and 1640–41, being returned for Kildare borough and Kildare county respectively. In the first session of the 1634 parliament he sat on a number of committees and supported the measures of the lord deputy, Thomas Wentworth (qv). In 1640 he was appointed captain of an army assembled by Wentworth to help subdue the Scottish covenanters. After the first session of the 1640–41 parliament he played a key role in the opposition to Wentworth. On 27 February 1641 he was on the committee nominated to prepare articles of impeachment against Sir Richard Bolton (qv), Gerard Lowther (qv), Sir George Radcliffe (qv), and Bishop John Bramhall (qv).
After the outbreak of rebellion in October 1641, the government supplied Fitzgerald with arms to defend Kildare. Instead he joined the rebels and surprised Naas in December 1641, although he soon had to withdraw at the approach of government forces. Both Lord Lambart (qv) and Capt. Jones sent messengers to his castle asking him to support the government, but Fitzgerald had gone into hiding and had left twenty musketeers to guard his residence. In 1642 he was one of the original signatories of the oath of confederation and commanded a company for the confederates. He became chief governor of Kildare and was appointed to the provincial council of Leinster on 11 November 1642. The same year he captured Monasterevin with his company. For his activities in the confederation he was expelled from the house of commons on 22 June 1642, for high treason. In 1644 and 1647 he sat in the general assembly of the confederation. A Maurice Fitzgerald captained a company in the earl of Castlehaven's (qv) expedition to Ulster in 1644.
During his time in parliament Fitzgerald appears to have forged links with Wentworth's protestant enemies. In February 1642 Lord Lambert conveyed his property in Kilbeggan to him, in order to protect it from being destroyed by the rebels, and Sir Arthur Loftus defended Fitzgerald within the Irish government in 1642–3. Given these connections, it is not surprising that Fitzgerald was to be found on the Ormondist wing of the confederation. In July 1646 he was pointed out to the marquess of Ormond (qv) as someone who could be employed by him in Kildare after he had made his peace with the confederation. On 20 June 1648 he was among those who took the oath of association at Kilkenny, declaring that they would not be influenced by the excommunication by the papal nuncio Rinuccini (qv) of those who adhered to the second Ormond peace. During the brief civil war that split the confederacy in 1648, the men of Owen Roe O'Neill (qv) captured him at the siege of Falkland fort. However, he had been released by June–August 1649, when he appears near Athy discussing the validity of Rinuccini's excommunication with a Franciscan friar. He was killed at the battle of Rathmines in September 1649 while leading his company under Ormond's command.
Fitzgerald married (date unknown) Ellen, daughter of Thomas Butler, Lord Dunboyne; they had no children. His estates were confiscated during the interregnum but were returned to his brother and heir after the restoration.