FitzGibbon's role as Lord Chancellor of Ireland during the period of the 1798 rebellion is questionable. According to some, he supported a hardline policy which used torture, murder and to crush the rebellion , or that as Lord Chancellor, he had considerable influence on military affairs, and that martial law could not have been imposed without his consent. Others allege that as Lord chancellor, he had no say in military affairs and the Encyclopædia Britannica states that he was "neither cruel nor immoderate and was inclined to mercy when dealing with individuals", however the same source also states that "(Fitzgibbon).. "was a powerful supporter of a repressive policy toward Irish Catholics"". Fitzgibbon's former side was displayed by sparing the lives of the captured United Irish leaders, 'State prisoners', in return for their confession of complicity and provision of information relating to the planning of the rebellion. However, this willingness of the prisoners to partake of the agreement was spurred by the execution of the brothers John and Henry Sheares on 14 July 1798.