Admiral Penn had managed to accumulate a very considerable fortune, and as a result William, the eldest son, became a rich man. His family was a prominent one, he had many influential friends, and now had plenty of money; so it was thought that he would naturally become a cavalier and gentleman of fashion. He soon made it clear, however, that he meant to retain the simple way of living adopted by the Quakers. Friends of his own age made fun of him, saying it was preposterous that a man of his means and abilities should spend his time with such dull people as those of the new religion. Sir John Robinson, the Lieutenant of the Tower of London, said to him, "I vow, Mr. Penn, I am sorry for you; you are an ingenious gentleman, all the world must allow you and do allow you that, and you have a plentiful estate. Why should you render yourself unhappy by associating with such a simple people?"

"I confess," frankly answered Penn, "I have made it my choice to relinquish the company of those that are ingeniously wicked, to converse with those that are more honestly simple."

In those days men challenged each other to arguments over their religions much as they might have challenged each other to a duel. Penn enjoyed defending the Quaker cause in public. A Baptist preacher by the name of Ives denounced Penn and the Quakers in a sermon, and Penn sent him a challenge to argue the question in public.

Ives did not appear at the meeting, but his brother took his place, and, according to the rules of such arguments, had to speak first. When he had finished his argument, he, with some friends, left the hall, hoping to draw so many people away with him that few would be left to listen to his opponent. But the audience stayed to hear Penn, and he spoke so eloquently that he won the house over to his side, and cost Ives the support of many of his followers. The young Quaker was proving as convincing a speaker as he had already shown himself to be a vigorous writer. He was fast becoming a power in the new sect.

He soon found a bigger man than Ives to argue with, for as he traveled through Oxfordshire preaching the Quaker cause he came to the University of Oxford, where he had been a student, and learned that the young men there who were interested in Quakerism were treated worse than ever. The Vice Chancellor of Oxford thought that the Quakers might become a dangerous political party, and was doing all in his power to abolish the new religion. Penn wrote him a letter in which, with fiery ardor, he denounced the Vice Chancellor for his persecution of Quaker students, and followed it up with other broadsides of attack on all who held similar views. He was a militant character, and when he argued before a public meeting, or wrote a letter that was to be read by his opponents, he never hesitated to express himself as strongly as he knew how. So in his letter to the Vice Chancellor he gave himself free rein. He wrote: "Shall the multiplied oppressions which thou continuest to heap upon innocent English people for their peaceable religious meetings pass unregarded by the Eternal God? Dost thou think to escape his fierce wrath and dreadful vengeance for thy ungodly and illegal persecution of his poor children? I tell thee, no. Better were it for thee hadst thou never been born. Poor mushroom, wilt thou war against the Lord, and lift up thyself in battle against the Almighty? Canst thou frustrate his holy purposes, and bring his determination to nought? He has decreed to exalt himself by us, and to propagate his gospel to the ends of the earth." Fine, spirited words are these, worthy of the valiant courage of young William Penn!

Penn returned from Oxfordshire to London, and went one day to a meeting in Wheeler Street. He started to address the meeting, but no sooner had he begun than a sergeant marched in with a file of soldiers, dragged him from the platform, and carried him off to the Tower. That evening an officer and some musketeers marched him from the Tower to Sir John Robinson, the lieutenant, who asked him many questions, trying to make it appear that Penn was a dangerous man, who, unless he were checked, might turn out to be another Cromwell. Sir John, knowing that the Quakers were opposed to all oaths, called on Penn to swear that he would never take up arms against the king, and also to take a solemn oath that he would never try to make any change of government either in church or state. This oath Penn refused to take, saying that the Quakers were opposed to all fighting as well as oath-taking. "If I cannot fight against any man (much less against the king)," said he, "what need I to take an oath not to do it? Should I swear not to do what is already against my conscience to do?"

Sir John and the other judges sneered at him, told him that he was bringing an honorable name to disgrace, and treated his principles with haughty contempt. Finally Sir John said, "But you do nothing but stir up the people to sedition; and one of your friends told me that you preached sedition and meddled with the government."

Penn looked these accusers squarely in the face. "We have the unhappiness to be misrepresented," he answered, "and I am not the least concerned therein. Bring me the man that will dare to justify this accusation to my face, and if I am not able to make it appear that it is both my practice and all my friends' to instill principles of peace and moderation (and only war against spiritual wickedness, that all men may be brought to fear God and work righteousness), I shall contentedly undergo the severest punishment all your laws can expose me to.

"As for the king, I make this offer, that if any living can make it appear, directly or indirectly, from the time I have been called a Quaker (since from thence you date me seditious), I have contrived or acted anything injurious to his person, or the English government, I shall submit my person to your utmost cruelties, and esteem them all but a due recompense. It is hard that I, being innocent, should be reputed guilty; but the will of God be done. I accept of bad reports as well as good."

But he could not make Sir John and the other judges believe in his innocence. "You will be the heading of parties and drawing people after you," said Sir John, doggedly, and ordered Penn taken to Newgate, the worst prison in London, where Quakers were herded with criminals of the lowest types.

People with money could hire rooms for themselves at Newgate and so avoid some of the discomforts of that vile place, and Penn spoke to his jailers about having a private room, but they answered him so abusively and insultingly and charged him so much for a private room that he said he preferred to share the lot of the poorest criminals. And there this man of wealth and education bravely stayed for six months, writing a number of essays and a spirited religious pamphlet. When the authorities thought the incorrigible young man must surely have learned his lesson in the wretched prison, they set him free again. He had spent half of the last three years in jails.

When he was at length liberated, he went abroad for a time, traveling in Holland and Germany, perhaps because his stay in Newgate had injured his health, perhaps to give the suspicions concerning him a chance to disappear. Yet, even on these journeys, whenever Penn found people showing any interest in the Quaker faith, he stopped and explained it fully to them. But in most places the new sect was looked upon as something very strange, and its members were suspected of designs against the government, so very few were anxious to learn about it.

In the autumn of 1671 Penn returned to England, and, for the first time in a number of years, lived a quiet life, giving over preaching and arguing and writing fiery pamphlets. He was twenty-seven years old, and he had fallen in love with a Quaker girl named Gulielma Maria Springett, or, as she was called by her friends, Guli Springett. Penn now busied himself in looking about for a suitable home in which to start housekeeping.

The father of William Penn's sweetheart was a young Puritan officer, who had been killed when only twenty-three years old at the siege of Bamber. Guli was born a few weeks later. Her mother, like many other people at that time, was neither satisfied with the religion of the Church of England nor that of the Puritans. Some time after her husband's death she married Isaac Pennington, and both became Quakers. So Guli was brought up in the new religion. They all lived quietly in Buckinghamshire until his neighbors began to complain to the authorities that Isaac Pennington was "talking Quaker doctrines." Then he was put in prison, and his wife and Guli wandered from one place to another.

Guli had a considerable fortune, and her charms brought her many suitors, even though her stepfather had fallen under the displeasure of the government. But she preferred the young and ardent Quaker who had himself suffered imprisonment so often in the same good cause; and in the spring of 1672 Guli and William were married. They made their home in the country, at Rickmansworth in Hertfordshire. They were comfortably well-to-do, and as the marriage was a very happy one, it might have been predicted that William Penn would become a prosperous country squire and have done with all religious discussions that were so likely to lead to a cell in the Tower of London.

At about the same time the king, Charles II., issued a proclamation, which was known as the Declaration of Indulgence, by the terms of which he did away with all the laws against the Quakers, Presbyterians, Baptists, Roman Catholics, and all who dissented from the Church of England. There was only one objection to this decree, and that was that the king issued it by his own act, and without the approval of Parliament, which meant that Charles II. had it in mind to try to rule without Parliament if it could be managed. The Declaration of Indulgence released over four hundred Quakers from prison, and in view of that benefit Penn and others were willing to overlook for the time the king's attempt to rule solely by his own will.

From his home in the country Penn began to make short trips through Kent and Sussex and Surrey, preaching the Quaker doctrines, a free lance who served without pay and purely because he loved the work. Occasionally he took his wife with him on his travels. They went together to Bristol to welcome the Quaker leader George Fox on his return from America, and hear from him what progress the new faith was making in the strange new country across the Atlantic Ocean.

By this time the Quakers had gained so many converts that the other sects were beginning to be afraid of them, and continually challenged them to more and more of those strange public debates in which the speakers did not hesitate to call their opponents harsh names. It was said of Penn that "he never turned his back in the day of battle," and he apparently threw himself into these arguments with the same ardor his ancestors had shown in warfare. Besides taking up the cudgel in defense of the new creed, he wrote many pamphlets and letters to people who disapproved of the Quakers. In this way he kept himself very busy during the two years he lived at his charming country home.

Charles II.'s Declaration of Indulgence proved so unpopular with the Parliament that the king had soon to withdraw it, and then the old opposition to all rivals of the Church of England broke out more violently than ever. George Fox was arrested and kept in prison for a year. The king offered to give him a pardon, but the Quakers were unwilling to accept pardons, as that would imply that they had really done something that was wrong. But Fox was ill, and Penn and some others went to court and tried to secure the favor of the Duke of York in behalf of Fox. The duke was very friendly to Penn, as he had been to Penn's father, but he did nothing to free Fox. However, the Quakers soon afterward secured the release of their leader by an appeal to the law courts.

Then a man named Richard Baxter happened to go to Rickmansworth and found the place "abounding with Quakers," as he put it, "because Mr. W. Penn, their captain, dwelleth there." Baxter wanted to redeem these people from their errors and challenged Penn to an argument. They debated from ten in the morning until five in the afternoon, before a great crowd, and at the end of that time all present held to their original views, although each debater claimed the victory. Penn enjoyed this argument immensely, for he told Baxter he would like to give him a room in his house, so "that I could visit and get discourse with thee in much tender love." But Baxter did not accept that invitation, and soon afterward Mrs. Penn inherited a house and estate at Worminghurst, in Sussex, so she and her husband moved their home to that place. A little later Penn, with George Fox and other Quakers, set out on a missionary visit to Holland and Germany.