[4] As a leading republican of the Dutch States Party, De Witt opposed the House of Orange-Nassau and the Orangists and preferred a shift of power from the central government to the regenten.

De Witt's mother was Anna van den Corput (1599–1645), niece of Johannes Corputius, an influential Dutch military leader and cartographer.

Through the marriage of one of his other uncles to Margaretha of Nassau, daughter of Anna Johanna of Nassau-Siegen, De Witt was a distant relative of William of Orange-Nassau.

[12] Johan and his older brother Cornelis grew up in a privileged environment in terms of education, his father having as good acquaintances important scholars and scientists, such as Isaac Beeckman, Jacob Cats, Gerardus Vossius, and Andreas Colvius.

After attending the Latin school in Dordrecht, Johan de Witt studied at the Leiden University, where he excelled at mathematics and law.

[15] In 1650 (the year that stadtholder William II, Prince of Orange died) he was appointed leader of the deputation of Dordrecht to the States of Holland and West Friesland.

The raadpensionaris of Holland was often referred to as the Grand Pensionary by foreigners as he represented the preponderant province in the Union of the Dutch Republic.

They were:[22] At the height of the Dutch Golden Age, the First Stadtholderless Period from 1650 to 1672, political power within Holland rested primarily with two pro-state minded, republican, families.

In one respect, however, he differed from his uncle, for although De Witt was a supporter of liberty like him, in contrast to him he clung to the extreme, which was to prove to be a fatal error in the Rampjaar 1672.

This class broadly coincided politically with the "States faction", stressing Protestant religious moderation and pragmatic foreign policy defending commercial interests.

Although leaders that did emerge from the House of Orange rarely were strict Calvinists themselves, they tended to identify with Calvinism,[29] which was popular among the middle classes in the United Provinces during this time.

The Lord Protector of England, Oliver Cromwell, demanded as a condition that the House of Orange should be permanently excluded from power in the Dutch Republic.

[32][33] As a result of the positive course of the war for the Netherlands, the Dutch leadership around De Witt, De Graeff, the army commander Johann Wolfart van Brederode and Lieutenant Admiral Jacob van Wassenaer Obdam urged the Dutch States General to position themselves as a whole behind the secret Act of Seclusion, which would exclude the young William III from the office of stadtholder.

In 1658/59 he sent large naval forces to the Baltic Sea to support Denmark against Sweden in the Second Northern War and to ensure free passage for Dutch merchant ships through the Øresund.

De Witt created a strong Dutch States Navy, appointing one of his political allies, Lieutenant Admiral Van Wassenaer Obdam, as supreme commander of the Confederate fleet.

One of his brothers-in-law, Jean Deutz, was a trusted advisor on economic matters[36] and financed the wars of the republic under his brother-in-law De Witt.

[40] Influenced by the values of the Roman republic, De Witt did his utmost anyway to prevent any member of the House of Orange from gaining power, convincing many provinces to abolish the stadtholderate entirely.

He allegedly contributed personally to the Interest of Holland, a radical republican textbook published in 1662, by his supporter Pieter de la Court.

De Witt reformed the Dutch naval forces by building larger and more heavily armed warships modelled after the English navy.

This was not without danger because French politics at that time was characterized by unbridled expansionism, which was reinforced by the formidable economic competition of the Dutch Republic.

Johan de Witt tried to guarantee the safety of the Republic with a pro-French policy but did not want to agree with King Louis XIV's plan to divide the Spanish Netherlands.

Only if Louis XIV rejected this and prolonged the War of Devolution to take control of the whole area would the three countries take military force against France.

His brother Cornelis (who was deputy-in-the-field for de Ruyter at the Raid on the Medway), particularly hated by the Orangists, was arrested on trumped-up charges of treason.

When his brother went over to the jail (which was only a few steps from his house) to help him get started on his journey, both were attacked by members of The Hague's civic militia.

Their naked, mutilated bodies were strung up on the nearby public gibbet, while the Orangist mob ate their roasted livers in a cannibalistic frenzy.

The demonstrations delivered petitions that demanded certain additional reforms with a, in a sense, "reactionary" flavour: the "ancient" privileges of the guilds and civic militias – who were traditionally seen as mouthpieces of the citizenry as a whole – to curb the regent's powers were to be recognised again (as in pre-Burgundian times).

The demonstrators also demanded more influence of the Calvinist preachers on the content of government policies and a roll-back of the toleration of Catholics and other dissenting denominations.

The purges of the city governments were not everywhere equally thoroughgoing (and, of course, there was little mention of popular influence later on, as the new regents shared the abhorrence of the old ones of real democratic reforms).

Only when the inundations froze over in the following winter was there, briefly, a chance for Marshal Luxembourg, who had taken over command of the invading army from Louis, to make an incursion with 10,000 troops on skates.

Meanwhile, the States General managed to conclude alliances with the German emperor and Brandenburg, which helped relieve the French pressure in the East.