The Amboise conspiracy, also called Tumult of Amboise, was a failed attempt by a Huguenot faction in France to gain control over the young King Francis II and to reverse the policies of the current administration of Francis, Duke of Guise and Charles, Cardinal of Lorraine through their arrest, and potentially execution. Malcontent factions of Huguenots had been chafing under the French crown since the reign of Henry II and with the arrival of a new young king, saw their chance to take power for themselves. However the plot was uncovered ahead of time, and the Guise were ready for them. As such hundreds would be arrested, and many killed. Louis I, Prince of Condé was suspected of involvement, however he was able to flee south, and it was only after some months that the Guise were able to put him on trial. Shortly thereafter, the sickly Francis II died, their hold on the administration collapsed, and with it the conviction of Condé. This tumult would be one of the key steps in the collapse of crown authority that led to the first French War of Religion.

On 10 July 1559, after a jousting accident, Henry II of France died suddenly. Premature as his death was, the crown fell to his young son, Francis II, who was only 15 years old, but legally of age to rule. Francis' wife's maternal uncles, Francis, Duke of Guise and Charles, Cardinal of Lorraine moved into the power vacuum, taking control over the young and sickly king's administration. They were faced with a formidable crisis; France was 40 million livres in debt, of which 19 million was owed immediately as a result of the Italian Wars. Many royal officials had been without pay for years. Along with this fiscal crisis, the Guise administration was faced with a religious crisis. Despite the persecutions undertaken by Henry II, Protestantism had continued to grow towards the end of his reign, leaving to the new administration the crisis of solving the religious question.

To solve these twin problems, the Guise set upon a course of religious political continuity, and fiscal cost cutting. The former embodied in four laws in the latter half of 1559, with landlords to be prosecuted if they harboured heretics and meeting houses to be razed to the ground among other provisions. Raids were conducted of suspected Protestant homes, and in Paris these found pamphlets, lambasting the Guise. The trial of the Protestant judge Anne du Bourg which ended in his execution in December after he refused to recant, further fanned the flames of religious tension, which exploded in the capital with the Saint-Médard riot later that month and the assassination of President (of the Parlement) Minard. The backlash to these policies, and the increasing militancy of some Protestants troubled the Guise, who issued new laws, banning the wearing of masks, and long coats that might conceal pistols.

On the financial side the Guise made equally many enemies, the army was drastically scaled down in size, and payments to troops were deferred, upsetting many soldiers. Some came to the royal residence to voice their displeasure, and were threatened by Lorraine with hanging if they didn't vacate the premises. Further, many of the cuts to the administration and new taxes had notable exemptions for the lands of the Guise, and their clients, angering those elites, who were not among their circles. Crown lands were resumed, with the exception of Guises' holdings of Saumur, Provins and Dourdan further alienating those elites who had benefited from such crown grants. Finally venal office was suppressed, a move which inflamed the title holders who lost their privileges.

No sooner had Henry II died than malcontent factions began to form against the new Guise led government. Those opposed to the Guise sought for Antoine of Navarre to become regent of the kingdom, conscious of his flirtations with Protestantism in the late 1550s. This was despite Francis II being of legal age to rule. This faction further desired the calling of an Estates General, to solve many of what they perceived as the kingdom's ills in the past decades. The Guise's alienation of elements of the army through their fiscal policy furthered this disgruntled clique, bringing into their number Maligny and Castelnau among others.

Around August 1559 a plan began to consolidate for the coup plot, aiming at first to assert Navarre's right to a regency, and, when he proved uninterested, Condé's more dubious right as a minor prince of the blood. La Renaudie was tasked to lead this coup attempt. He had personal reasons to want to see the Guise taken from power, the Cardinal of Lorraine having had his brother-in-law executed. La Renaudie boasted that he had the support of John Calvin in Geneva and was given an angry reception when he visited the city hunting for recruits late in the year.

The large part of the ideological support base for the coup came from petit seigneurs such as de Mauvans and Protestant clerics, such as Antoine de la Roche Chandieu. Alongside military malcontents often from their retinues or clients, many poor soldiers were easily tempted by La Renaudie's offer of 10 sous for infantry and 18 sous for cavalry. The church of Provence was the only consistory to be fully onboard, the region, one of great Protestant strength, offering 2000 soldiers to the cause of the coup. Gaspard II de Coligny who had come to terms with the Guise recently was uninterested in involving himself, and did his best to persuade the Protestant nobility of Normandy in his powerbase to stay clear of involvement.

On 1 February the conspirators met in the forests near Nantes for a 'Parliament' during which the baron du Raunay offered his nearby château as a springboard for the operation and all participants swore an oath. The location was chosen to coincide with the meeting of the nearby Parlement, to explain the conspirators' presence in the area.