- "All men dream of thrones. It is in our nature."
- ―Stephane Chapheau[src]
A monarchy is a form of government in which the head of state is a monarch. Although it is normally typified by hereditary succession, some monarchies in history have been elective.
Monarchy was the most common form of government for most of human history, with societies across the world, from the Aztecs to England, Egypt to Rome, Iran to China, establishing their states around it. 
Despite the nominally autocratic nature of the monarch, they did not always wield absolute power. Whether formally or informally, they could be constrained by the nobles immediately below them, and the actual authority of monarchs varied widely depending on the state. In Sparta, the state was simultaneously led by two kings of separate dynasties who checked one another's power while its rival, Athens, transformed itself first from a monarchy to an aristocracy, then into the world's first democracy.
The Roman Kingdom gave way to the Roman Republic when its last king was overthrown by its incensed subjects. The Roman Republic in turn was eventually reconstituted as an empire with the monopolization of power by Augustus, who henceforth became known to history as the first Roman Emperor. Augustus and his successors maintained the illusion that the republic with all its divided offices still existed, as it did officially, and this gradual transition from republic to empire illustrates the blurring of the lines between dictatorial republics and non-absolute monarchies. 
With the collapse of the Western Roman Empire, Italy disintegrated into numerous diverse states, not all of which were monarchies. Some, like the Republic of Venice and Republic of Florence, operated with unique mixed government systems blending the democratic mechanics of ancient Athens with monarchy and oligarchy. 
In the Ottoman Empire, conflicts over succession between the sons of the ruler frequently exploded into violence, as exemplified by the fratricide of the Templar Grand Master Prince Ahmet by his elder brother, Selim, in 1512.
By the 18th century, the preeminence of monarchy was being increasingly challenged by philosophies developed in the Enlightenment which taught principles like the consent of the governed, natural rights, and separation of powers. The English Civil War in the mid-17th century led first to the replacement of the monarchy with a dictatorship and then to the restoration of the monarchy, but whose authority was now subordinate to the parliament. From this point, England, and its successor state the United Kingdom became what is now known as a constitutional monarchy. 
Nevertheless, anti-monarchism reached a height among the British colonists of North America in the late 18th century. Outrage over perceived injustices, including taxation without representation, were articulated through an Enlightenment liberal lens, eventually erupting in the American Revolution. The victory of the rebels in 1783, assisted by the Colonial Brotherhood of Assassins, secured their secession from the British Empire as the United States of America, a republic that would inspire many new anti-monarchical revolutions to come. Its first president, George Washington, was not immune to the lure of monarchy, but after witnessing a vision of an alternative future where he reigned as a tyrannical king and fought with his Assassin ally, Ratonhnhaké:ton, he resolutely rejected this temptation.
At the heels of the American Revolution was the French Revolution that began in 1789. Unlike the American Revolution, this movement witnessed widespread chaos and bloodshed as a series of regimes were rapidly switched out one after another. The failure of France's experiment with constitutional monarchy from 1789 to 1792 culminated in the execution of King Louis XVI in January 1793. Thereupon witch-hunts against perceived "anti-revolutionaries" or "royalists" ensued, climaxing with the Reign of Terror under Maximilien de Robespierre. With each circle of less radical revolutionaries purged one by one, Robespierre inched closer and closer to slaughtering his own supporters, and he suddenly met his downfall in the summer of 1794.
His execution ended the Terror, but the regime that replaced it out of self-preservation was corrupt and ineffectual, and these conditions allowed for the rise of Napoleon Bonaparte as the first Emperor of the French in 1804. As a result, the French Revolution saw the fall of one monarchy and the rise of another, albeit one infused with republican advances. France would subsequently experience more revolutions throughout the long 19th century, eventually settling into the French Fifth Republic of today. 
A Templar revolution
- "For centuries we've focused our attentions on the trappings of power: the titles of nobility, the offices of Church and State. So obsessed with clinging to the trappings of power we abandoned our purpose. Caught in the very lie we crafted to shepherd the masses."
- ―François-Thomas Germain[src]
Behind the scenes of the French Revolution was yet another revolution, one situated within the Templar Order itself. The shadow organization had for millennia operated by infiltrating the courts of monarchies, using nobles and rulers as their puppets whereas their mortal adversaries, the Assassins tended to ally themselves with the common people. This changed in 1789 with a schism within the Order initiated by François-Thomas Germain, who had Grand Master François de la Serre assassinated by his supporters. Having taken over the Parisian Rite, Germain incited some of the worst violence in the French Revolution—Robespierre, himself, was one of his agents.
Through both the French Revolution and his own coup in the Templar Order, he inaugurated a new era whereby the Templars no longer manipulated the world through nobles but could do so through a new emerging elite of powerful corporatists. The French Revolution, then, was a pivotal moment in human geopolitics, as it heralded not just the decline of monarchies but also the Templars' reorganization as Abstergo Industries in 1937.