Despite the fact that both groups of the Jacobin Club had virtually no difference with regard to the establishment of the French Republic, the aggressive military intentions of the rich merchant class-backed Girondins, such as conquering the Rhineland, Poland and the Netherlands with a goal of creating a protective ring of satellite republics in Great Britain, Spain, and Italy,[11] and a potential war with Austria,[12] enabled the Montagnards to take over the administrative power of the National Convention under the leadership of Maximilien Robespierre who openly advocated for a more peaceful external policy and rather focusing on the issues within the newly-founded First French Republic.

The Girondins had wanted to avoid the execution of Louis XVI and supported a constitution that would have allowed a popular vote to overturn legislation.

[22] Following their coup, the Mountain, led by Hérault de Séchelles, quickly began construction on a new constitution which was completed eight days later.

Would-be prominent Montagnard leaders like Jean-Baptiste Robert Lindet and Jean Bon Saint-André were tempted by early Girondin proposals and soon many moderates—even anti-radicals—felt the need to push for radical endeavors in light of threats both within and without the country.

[28] It was only after the trial of Louis XVI in December 1792, which united the Montagnards on a position of regicide, that the ideals and power of the group fully consolidated.

[29] On 24 February the Convention decreed the first albeit unsuccessful Levée en Masse, triggering uprisings in rural France as the Montagnards' influence waned in Marseille, Toulon, and Lyon.

In August 1793, Montagnard member Jean Jacques Régis de Cambacérès drafted a piece of legislation which dealt with agricultural reform; in particular, he urged "relief from rent following harvest loss, compensation for improvements and fixity of tenure".

This draft never made it into law, but the drastic reforms suggest the Mountain's awareness of the need to please their base of support, both the rural and urban poor.

[20] At the same time, bread prices were rising as the commodity became scarce, and in an initiative spearheaded by Collot d'Herbois and Billaud-Varenne, a law was enacted in July 1793 that forbade the hoarding of "daily necessities".

These policies varied but began with a ban on religion, allowing only for "the worship of Reason" in 1793 and progressing to religious freedom with the separation of Church and State in 1795.

[37] The fall and exclusion of the Montagnards from the National Convention began with the collapse of the Revolution's radical phase and the death of Robespierre on 10 Thermidor (28 July 1794).

While the Montagnards celebrated unity, there was growing heterogeneity within the group as the Committee of Public Safety extended themselves with their tight control over the military and their extreme opposition to corruption in the government.

[38] Their extension drew the ire of other revolutionary leaders and a number of plots coalesced on 9 Thermidor (Thermidorian Reaction) when collaborators with the more moderate group the Dantonists acted in response to fears that Robespierre planned to execute them.

[28] Finally, at the end of 1794 the Mountain largely devolved into a group called The Crest (French: crête), which lacked any real power.