Pope Innocent III in the context of "Albigensian Crusades"

Mendicant orders are primarily certain Catholic religious orders that have vowed for their male members a lifestyle of poverty, traveling, and living in urban areas for purposes of preaching, evangelization, and ministry, especially to less wealthy individuals. At their foundation these orders rejected the previously established monastic model, which prescribed living in one stable, isolated community where members worked at a trade and owned property in common, including land, buildings and other wealth. By contrast, the mendicants avoided owning property, did not work at a trade, and embraced a poor, often itinerant lifestyle. They depended for their survival on the goodwill of the people to whom they preached. The members of these orders are not called monks but friars.

The term "mendicant" is also used with reference to some non-Christian religions to denote holy persons committed to an ascetic lifestyle, which may include members of religious orders and individual holy persons.

Magna Carta (Medieval Latin for "Great Charter"), sometimes spelled Magna Charta, is a royal charter of rights sealed by King John of England at Runnymede, near Windsor, on 15 June 1215. First drafted by the Archbishop of Canterbury, Cardinal Stephen Langton, to make peace between the unpopular king and a group of rebel barons who demanded that the King confirm the Charter of Liberties, it promised the protection of church rights, protection for the barons from illegal imprisonment, access to swift and impartial justice, and limitations on feudal payments to the Crown, to be implemented through a council of 25 barons. Neither side stood by their commitments, and the charter was annulled by Pope Innocent III, leading to the First Barons' War.

After John's death, the regency government of his young son, Henry III, reissued the document in 1216, stripped of some of its more radical content, in an unsuccessful bid to build political support for their cause. At the end of the war in 1217, it formed part of the peace treaty agreed at Lambeth, where the document acquired the name "Magna Carta", to distinguish it from the smaller Charter of the Forest, which was issued at the same time. Short of funds, Henry reissued the charter again in 1225 in exchange for a grant of new taxes. His son, Edward I, repeated the exercise in 1297, this time confirming it as part of England's statute law. However, Magna Carta was not unique; other legal documents of its time, both in England and beyond, made broadly similar statements of rights and limitations on the powers of the Crown. The charter became part of English political life and was typically renewed by each monarch in turn. As time went by and the fledgling Parliament of England passed new laws, it lost some of its practical significance.

The Fourth Crusade (1202–1204) was a Latin Christian armed expedition called by Pope Innocent III. The stated intent of the expedition was to recapture the Muslim-controlled city of Jerusalem, by first defeating the powerful Egyptian Ayyubid Sultanate. However, a sequence of economic and political events culminated in the Crusader army's 1202 siege of Zara and the 1204 sack of Constantinople, rather than the conquest of Egypt as originally planned. This led to the partition of the Byzantine Empire by the Crusaders and their Venetian allies, leading to a period known as the Frankokratia ("Rule of the Franks" in Greek).

In 1201, the Republic of Venice contracted with the Crusader leaders to build a dedicated fleet to transport their invasion force. However, the leaders greatly overestimated the number of soldiers who would embark from Venice, since many sailed from other ports, and the army that appeared could not pay the contracted price. In lieu of payment, the Venetian Doge Enrico Dandolo proposed that the Crusaders back him in attacking the rebellious city of Zara (Zadar) on the eastern Adriatic coast. This led in November 1202 to the siege and sack of Zara, the first attack against a Catholic city by a Catholic Crusader army, despite Pope Innocent III's calls for the Crusaders not to attack fellow Christians. The city was then brought under Venetian control. When the Pope heard of this, he temporarily excommunicated the Crusader army.

An overlord in the English feudal system was a lord of a manor who had subinfeudated a particular manor, estate or fee, to a tenant. The tenant thenceforth owed to the overlord one of a variety of services, usually military service or serjeanty, depending on which form of tenure (i.e. feudal tenancy contract) the estate was held under. The highest overlord of all, or lord paramount, was the monarch, who due to his ancestor William the Conqueror's personal conquest of the Kingdom of England, owned by inheritance from him all the land in England under allodial title and had no superior overlord, "holding from God and his sword", although certain monarchs, notably King John (1199–1216) purported to grant the Kingdom of England to Pope Innocent III, who would thus have become overlord to English monarchs.

A paramount lord may then be seen to occupy the apex of the feudal pyramid, or the root of the feudal tree, and such allodial title is also termed "radical title" (from Latin radix, root), "ultimate title" and "final title". William the Conqueror immediately set about granting tenancies on his newly won lands, in accordance with feudal principles. The monarch's immediate tenants were the tenants-in-chief, usually military magnates, who held the highest status in feudal society below the monarch. The tenants-in-chief usually held multiple manors or other estates from the monarch, often as feudal barons (or "barons by tenure") who owed their royal overlord an enhanced and onerous form of military service, and subinfeudated most to tenants, generally their own knights or military followers, keeping only a few in demesne. This created a mesne lord – tenant relationship. The knights in turn subinfeudated to their own tenants, creating a further subsidiary mesne lord – tenant relationship. Over the centuries for any single estate the process was in practice repeated numerous times.

Papal income tax was first levied in 1199 by Pope Innocent III, originally requiring all Catholic clergy to pay one-fortieth of their ecclesiastical income annually in support of the Crusades. The second income tax was not levied until the Fourth Lateran Council in 1215, and constituted only a triennial twentieth.

This precedent was frequently continued by the successors of Innocent III, enforced by ecclesiastical censure, by sequestration, and frequently by the use of force. The first time the tax was imposed, contributors were promised that a quarter of the penances would be rebated if payments were made willingly and honestly; the second time, non-compliance was simply threatened with excommunication. On a few occasions popes convoked a general council before imposing an income tax, but more often imposed the tax solely on their own authority.

The Fifth Crusade (September 1217 – August 29, 1221) was a campaign in a series of Crusades by Western Europeans to reacquire Jerusalem and the rest of the Holy Land by first conquering Egypt, ruled by the powerful Ayyubid sultanate, led by al-Adil, brother of Saladin.

After the failure of the Fourth Crusade, Innocent III again called for a crusade, and began organizing Crusading armies led by Andrew II of Hungary and Leopold VI of Austria, soon to be joined by John of Brienne, titular King of Jerusalem. An initial campaign in late 1217 in Syria was inconclusive, and Andrew departed. A German army led by cleric Oliver of Paderborn, and a mixed army of Dutch, Flemish and Frisian soldiers led by William I of Holland, then joined the Crusade in Acre, with a goal of first conquering Egypt, viewed as the key to Jerusalem. There, cardinal Pelagius Galvani arrived as papal legate and de facto leader of the Crusade, supported by John of Brienne and the masters of the Templars, Hospitallers and Teutonic Knights. Holy Roman Emperor Frederick II, who had taken the cross in 1215, did not participate as promised.

The University of Paris (French: Université de Paris), known metonymically as the Sorbonne (French: [sɔʁbɔn]), was the leading university in Paris, France, from 1150 to 1970, except for 1793–1806 during the French Revolution. Emerging around 1150 as a corporation associated with the cathedral school of Paris, it was considered the second-oldest university in Europe. Officially chartered in 1200 by King Philip II and recognised in 1215 by Pope Innocent III, it was nicknamed after its theological College of Sorbonne, founded by Robert de Sorbon and chartered by King Louis IX around 1257.

Highly reputed internationally for its academic performance in the humanities ever since the Middle Ages – particularly in theology and philosophy – it introduced academic standards and traditions that have endured and spread, such as doctoral degrees and student nations. Notable popes, royalty, scientists, and intellectuals were educated at the University of Paris. A few of the colleges of the time are still visible close to the Panthéon and Jardin du Luxembourg: Collège des Bernardins (18 rue de Poissy, 5th arr.), Hôtel de Cluny (6 Place Paul Painlevé, 5th arr.), Collège Sainte-Barbe (4 rue Valette, 5th arr.), Collège d'Harcourt (44 Boulevard Saint-Michel, 6th arr.), and Cordeliers (21 rue École de Médecine, 6th arr.).