The Mayhew Restoration was Protector Benjamin Mayhew IX of Grayson's reassertion of the provisions of the written Constitution concerning his powers as head of state and government, an event which led to the resumption of direct rule by the Protector over Grayson and the end of a century-long erosion of his power and authority by the Protector's Council and the Conclave of Steadholders.
While the planetary Constitution of Grayson granted the Protector with wide powers as the head of state and secular leader of the Church of Humanity Unchained, a series of weak Protectors during the 19th Century PD allowed the Council and the Conclave of Steadholders to gain virtual control of the government, leading the Protector to be reduced almost to a figurehead role. (HH2, HH5)
However, when Masada (supported by the People's Republic of Haven) launched a full-scale attack on Grayson in 1903 PD which almost completely destroyed the Grayson Space Navy, the Grayson government was forced to turn to the only help available: a squadron of Manticoran warships which had arrived to Yeltsin's Star as part of a diplomatic mission to secure a treaty of alliance between Grayson and Manticore.
Following the death of the Manticoran envoy to Grayson, Admiral Raoul Courvosier, the Manticoran squadron was led by Captain Honor Harrington, commanding officer of the heavy cruiser HMS Fearless. Coupled with her virtual ultimatum to leave Grayson to its own fortune unless she was allowed to meet with the Protector, Harrington's condition as a woman serving in the Manticoran military (which was in full defiance of Grayson's mores) led to a virtual standstill of the Council regarding the decision to accept Harrington's terms.
The deadlock allowed Protector Benjamin to take matters in his own hands, and his decision to accept a meeting with Captain Harrington without the "consent" of his Council (which he was legally entitled to, under the Constitution) overturned a hundred years of constitutional and legal precedent, and allowed him to reassert his leadership during the Masadan conflict. (HH2)
After the war with Masada, a ruling by the High Court of Grayson confirmed Protector Benjamin's claim to direct rule as legal under the written Constitution, and with this legal backing (as well as the support of the Sacristy of the Church) the Protector set out to reassert the power of his office and of the central government. (HH5)
A number of Steadholders, including Lord Burdette and Lord Mueller, coalesced into opposition to the Restoration, and at several times these Steadholders tried to reverse the political balance of power into another more favorable to their interests. (HH5, HH9)