Penn, an advocate of democracy and religious freedom, was known for his amicable relations and successful treaties with the Lenape Native Americans who had resided in present-day Pennsylvania prior to European settlements in the state.

Penn's Quaker government was not viewed favourably by the previous Dutch, Swedish and English settlers in what is now Delaware, and in addition to this, the land was claimed for half a century by the neighboring Province of Maryland's proprietor family, the Calverts.

[3] Penn was imprisoned several times in the Tower of London due to his faith, and his book No Cross, No Crown, published in 1669, which he authored from jail, has become a classic of Christian theological literature.

[13] Their neighbor was the diarist Samuel Pepys, who was friendly at first but later secretly hostile to the Admiral, perhaps embittered in part by his failed seductions of both Penn's mother and his sister Peggy.

[21] Penn returned home for the extraordinary splendor of the King's restoration ceremony and was a guest of honor alongside his father, who received a highly unusual royal salute for his services to The Crown.

When theologian John Owen was fired from his deanery, Penn and other open-minded students rallied to his side and attended seminars at the dean's house, where intellectual discussions covered the gamut of new thought.

[30] Upon returning to England after two years abroad, he presented to his parents a mature, sophisticated, well-mannered, modish gentleman, though Samuel Pepys noted young Penn's "vanity of the French".

[36] His first experience of warfare gave him the sudden idea of pursuing a military career, but the fever of battle soon wore off after his father discouraged him, "I can say nothing but advise to sobriety...I wish your youthful desires mayn't outrun your discretion.

The times sprouted many new sects besides Quakers, including Seekers, Ranters, Antinomians, Seventh Day Baptists, Soul sleepers, Adamites, Diggers, Levellers, Behmenists, Muggletonians, and others, as the Puritans were more tolerant than the monarchy had been.

Between 1671 and 1677, Penn visited Germany on behalf of the Quaker faith, resulting in a German settlement in the Province of Pennsylvania that was symbolic in two ways: It was a German-speaking congregation, and it included religious dissenters.

[61] In 1668, in a letter to the anti-Quaker minister Jonathan Clapham, Penn wrote: "Thou must not, reader, from my querying thus, conclude we do deny (as he hath falsely charged us) those glorious Three, which bear record in heaven, the Father, Word, and Spirit; neither the infinity, eternity and divinity of Jesus Christ; for that we know he is the mighty God.

From then on, Penn's religious views effectively exiled him from English society; he was expelled from Christ Church, a college at the University of Oxford, for being a Quaker, and was arrested several times.

[72] This case was one of the more important trials that shaped the concept of jury nullification[73] and was a victory for the use of the writ of habeas corpus as a means of freeing those unlawfully detained.

[84]: 64  Penn became the sole proprietor of a huge tract of land west of New Jersey and north of the Province of Maryland belonging to Lord Baltimore, and gained sovereign rule of the territory with all rights and privileges with the exception of the power to declare war.

[85] In return, one-fifth of all gold and silver mined in the province, which had virtually none, was to be remitted to the King, and the Crown was freed of a debt to the Admiral of £16,000, equal to roughly £3,167,726 in 2025.

[87] On 4 March 1681, the King signed the charter and the following day Penn jubilantly wrote, "It is a clear and just thing, and my God who has given it to me through many difficulties, will, I believe, bless and make it the seed of a nation.

[90] Having proved himself an influential scholar and theoretician, Penn now had to demonstrate the practical skills of a real estate promoter, city planner, and governor for his "Holy Experiment", the province of Pennsylvania.

To attract settlers in large numbers, he wrote a glowing prospectus, considered honest and well-researched for the time, promising religious freedom as well as material advantage, which he marketed throughout Europe in various languages.

[94] Eventually he attracted other persecuted minorities including Huguenots, Mennonites, Amish, Catholics, Lutherans, and Jews from England, France, Holland, Germany, Sweden, Finland, Ireland, and Wales.

[95] Penn then began establishing the legal framework for an ethical society where power was derived from the people, from "open discourse", in much the same way as a Quaker Meeting was run.

[98] The laws of behavior he laid out were rather Puritanical: swearing, lying, and drunkenness were forbidden as well as "idle amusements" such as stage plays, gambling, revels, masques, cock-fighting, and bear-baiting.

[67] He borrowed liberally from John Locke who later had a similar influence on Thomas Jefferson, but added his own revolutionary idea – the use of amendments – to enable a written framework that could evolve with the changing times.

"[101] Penn hoped that an amendable constitution would accommodate dissent and new ideas and also allow meaningful societal change without resorting to violent uprisings or revolution.

[113] Accompanied by his wife Hannah, daughter Letitia and secretary James Logan, Penn sailed from the Isle of Wight on the Canterbury, reaching Philadelphia in December 1699.

[122] In 1718, at age 73, Penn died penniless, at his home in Ruscombe, near Twyford in Berkshire, and is buried in a grave next to his first wife, Gulielma, in the cemetery of the Jordans Quaker meeting house near Chalfont St Giles in Buckinghamshire.

They had nine children in twelve years: According to American historian Mary Maples Dunn: Penn liked money and although he was certainly sincere about his ambitions for a "holy experiment" in Pennsylvania, he also expected to get rich.

He was, however, extravagant, a bad manager and businessman, and not very astute in judging people and making appointments... Penn was gregarious, had many friends, and was good at developing the useful connections which protected him through many crises.

Among Penn's legacies was his unwillingness to force a Quaker majority upon Pennsylvania, allowing his state to develop into a successful melting pot, with multiple religions.

Thomas Jefferson and the Founding Fathers adopted Penn's theory of an amendable constitution and his vision that "all Persons are equal under God", as he informed the federal government following the American Revolution.

However, William's son and successor, Thomas Penn, and his brother John, renounced their father's faith, and fought to restrict religious freedom (particularly for Catholics and later Quakers as well).