Upon his father's death, Frederick inherited the proprietorship of Maryland, making him the sixth Lord Baltimore, and immense wealth and considerable political connections. His wealth included an income of about ten thousand pounds sterling a month, derived from collected rents and taxes, large shares of stock of the Bank of England, and his resident estate at Woodcote Park, in Surrey. It was through this wealth that enabled Frederick to live a life of high style and leisure.

Through this life of leisure, Frederick traveled extensively, but never visited Maryland. His travels took him throughout Europe, especially Italy where he would stay for long periods and Constantinople, where he lived for a while. Interestingly, Frederick's extravagant lifestyle actually interfered with his duties as the Proprietor of Maryland; however, at the same time he is credited with building Anglo-American relations in Maryland. The building of these relations, although believed to be accidental on Frederick's part, did come at a good time during the imperial crisis of the 1760s and 1770s. Although raised as a Catholic, he professed the Anglican faith to which his grandfather converted, to aid in regaining his proprietary colony after the crown held it.

Frederick had very good political ties, not only in London and throughout Europe, but also in Maryland. Three of Maryland's governors were related to him. Thomas Bladen, who served as governor from 1742 to 1752 married his aunt; Horatio Sharpe, governor from 1753-1769 was the brother of his guardian; and, Robert Eden, governor from 1769-1776, married his sister. Even though Lord Baltimore picked Robert Eden and Horatio Sharpe because of his relationship with them, they were good choices for the colonists of Maryland. Their relationship with the Lord Baltimore enabled them to easily solve problems between the proprietor and the colonists, at least to a point. However, because Frederick never visited Maryland, his attitudes and policies were responsible in shaping Maryland's reaction to the imperial crisis that led to the Revolution.

Although both Sharpe and Eden were very capable and well-liked governors, and maintained a good relationship with Frederick, they did become frustrated with Frederick. Frederick did abuse his trust the colonists had in him, which eventually distanced his colonial subjects. He did not allow Maryland to have an agent in London, which was the norm in many other colonies. He believed that taxation was a violation of his liberty, and thus refused his property or income to be taxed to support the war with France. He also refused to have the income he obtained from licensing redirected from his private holdings to help support the military costs.

Naturally, the colonists took exception to these policies believing them unfair, and the crown saw Frederick's actions as a hindrance to the war effort. It began apparent that Frederick's only goal was money, and not the interests of the colony.

One of Frederick's appointments, Bennett Allen, who was an Anglican clergyman, and good friend to Frederick, engaged in pluralism, by serving as pastor to several parishes at the same time, violating Maryland law and customs. Those that opposed Bennett would be threatened, that if they did not cooperate, Bennett would report their actions to Frederick, by virtue of his personal connections with him. Through repeated events such as this, the colonists respect for Frederick diminished, and tension arose among his governors.

Throughout these strained times, Frederick made himself difficult to contact. To avoid any confrontation, he traveled frequently, making it difficult for even his provincial secretary to locate him to conduct business.

Frederick's personal relationships were a disaster as well. In 1753 he married Lady Diana Egerton, the daughter of the Duke of Bridgewater. As he did not get along with his wife, he usually lived apart from her. Upon her death, he then lived with Hester Whalen of Ireland, with whom he had an illegitimate son and daughter. Additionally, by the year 1770, Frederick had twins by a different woman, and a daughter by another.

In Constantinople, because of his illegitimate children, scandals broke causing him to leave, as well as charges of him having his own private harem. These charges followed him to London as well. Frederick did support his illegitimate children, sending money to the stepfather of his heir Henry, by Hester Whalen.

In 1768, another scandal befell Frederick at home in London. This time he was accused of abduction and rape by Sarah Woodcock. During the trial, Frederick was tried as much by the press as he was in the courtroom. The jury, believing that Sarah did not make adequate attempts to escape or to report the crime properly, acquitted Frederick. To avoid any further disgrace, Frederick retreated to the continent.

On September 4, 1771, Frederick died in Naples, but unfortunately the many problems he created still existed for his colony. Before his death, Frederick made his illegitimate son Henry Harford, his heir. Using elaborate steps, Frederick instructed Governor Eden to declare the province of Maryland for Henry upon his death. The province of Maryland did recognize Henry as the heir, but his cousins, the Brownings, did not. Frederick's sister, Louisa Calvert, had married John Browning earlier. The Brownings, therefore contested the will, but were later bought off.

With the coming of the Revolution in 1774, Governor Eden left Maryland to pursue his own interests by initiating action on his wife's behalf in court, regarding her claim to her brother Frederick's estate. By leaving, he abandoned his colony to the revolutionaries. In his absence, the Loyalist cause and stabilizing force that Eden had thus far exerted on the Revolution was lost. Although Eden made a claim of Frederick's estate on his wife's behalf, this legal battle ended quickly when Sir Robert Eden decided to honor Frederick's instructions to him in his will, to recognize Henry as the true proprietor. All claims toward Frederick's estate against Henry made in 1774 and again in 1778, were finally settled in Henry's favor by Parliament through the Estate Act of 1780. As such, Henry received the bulk of his father's estate, totaling about 96,000 pounds.

Frederick Calvert can be credited with much of the unrest in Maryland that contributed to the anti-imperial attitudes that lead to American Independence. The colonists, once they displaced the proprietary authority, were reluctant to join the remaining colonies against the King of England.

Henry Harford, Frederick's illegitimate son by Hester was born April 5, 1758. Henry was raised, as was his sister, by Peter Prevost, Esq., their stepfather through marriage to their mother Hester. In caring for his son and daughter, Frederick paid large sums of money to Peter, who in turn raised them with all the advantages afforded the wealthy. Henry also was the heir to his father's fortune.

Henry attended Richmond School, in Surrey, then Eton, and Exeter College, Oxford University, where he obtained a degree in 1779. Following college, Henry ran for Parliament in 1781. Although he tied his opponent in the popular vote, he lost when the House of Commons decided the election. His opponent was favored due to him being a prominent land owner.

Although Henry inherited Maryland from his father in 1771, he paid little if any attention to his province, being only thirteen years old. Consequently, his uncle, Cecilius Calvert, Maryland's provincial secretary, managed his affairs. By the time Henry reached the age of majority, his province of Maryland had declared their independence and was at war with Great Britain. Because of his loyalty to the crown, Henry lost all his extensive property holdings in Maryland during the American Revolutionary War. However, having great wealth in England, he still was able to maintain the lavish life of a country gentleman.

In 1783, Henry and Sir Robert Eden returned to Maryland, where Henry tried to reclaim his land lost during the Revolutionary War. Believing it to be a simple task as the English courts settled in his favor, he soon learned that this claim would not come easily. Henry was however, accepted into the social circles upon his arrival in Annapolis. While there, he and Eden were the house guests of Dr. Upton Scott, at his elegant home. Dr. Scott was the uncle of Francis Scott Key, where Francis stayed while attending school in Annapolis in 1789. Having been accepted into the social graces of Annapolis, Henry was invited and attended the ceremony at Maryland's State House when George Washington resigned his commission as commander-in-chief on December 23, 1783.

In his attempt to regain his lost land, Henry petitioned the Maryland General Assembly in 1785. In this claim he also asked for lost rents on his land from 1771 until independence was declared. Henry's total claim was 327,441 pounds.

The assembly members reacted to Henry's claims with mixed emotions. One problem was that in 1780, the state had issued bills of exchange guaranteed by Henry Harford's confiscated property. So, if they returned the land to Henry, what then would happen if the bills of exchange were redeemed? This possibility made the assembly members nervous. Additionally, the Treaty of Paris, which ended the Revolutionary War, did not make clear the disposition of loyalists and their property claims.

In his request to the assembly, Henry wrote a letter by which he recognized the "free state" and appealed to "the dictates of equity and the feelings of humanity," citing that he needed this property for the "relief of his financial situation to avoid further embarrassments." This was a somewhat disputable statement in lieu of his considerable wealth.

Samuel Chase, a member of the Maryland Delegation, and one of four Marylanders who signed the Declaration of Independence, supported Henry's petition. It was felt that he did so to enhance his own chances as Maryland's agent to regain stock held in the Bank of England. Charles Carroll of Carrollton, another delegation member, and Maryland signer of the Declaration of Independence, also supported Henry's petition, which was consistent with his opposition to confiscation during the war. The petition received favorable votes in the House, but was unanimously rejected by the Senate in 1786. In their reasoning for this rejection, the Senate sited Henry's absence during the war, and his father, Frederick's alienation of his subjects, as major factors.

Having lost his petition in Maryland, Henry returned to England and attempted to gain compensation there. Following the Revolutionary War, Parliament established a system for reimbursing those loyalists who suffered losses during the war. In this claim, Harford and the Penn family, who also filed a claim, were recognized in Class VIII of the loyalists' losses that included proprietors. This classification was considered those of low risk, subject to a lower rate of compensation.

Henry Harford requested losses in the amount of 400,000 pounds, and the Penn family at 500,000 pounds. Over the next thirty years through litigation, Henry received more than 100,000 pounds, which turned out to be the second highest award given.

In 1792, Henry married Louisa Pigou, and through his inheritance, they lived a very comfortable life. Henry and Louisa had five children. Their first born son, Henry, died in infancy. Following Henry were Frederick Paul, Louisa Ann, Frances, and Fredericka Louisa Elizabeth.

In 1802, Henry's wife Louisa died. Four year's later, in 1806, Henry married Esther Ryecroft. They had two sons, George and Charles, and three daughters, Charlotte Penelope, Esther, and Emily.

At the time of the Revolution, Henry was too young to have taken an active role. Although the Revolution cost him his province, he still was able in later years to provide popular leadership that helped in shaping events. We remember Henry as Maryland's last proprietor, and the last trace of the Lords Baltimore's many failed attempts to bring supremacy to America.

Henry Harford is characteristic of the cost of loyalty to the crown, all the while having the position that permitted him to live a lavish lifestyle, in spite of his many losses.