George was born on 28 May 1660 in Hanover in the Holy Roman Empire. He was the eldest son of Ernest Augustus, Duke of Brunswick-Lüneburg, and his wife, Sophia of the Palatinate. Sophia was the granddaughter of King James I of England through her mother, Elizabeth of Bohemia.  For the first year of his life, George was the only heir to the German territories of his father and three childless uncles. In 1661 George’s brother, Frederick Augustus, was born and the two boys (known as Görgen and Gustchen within the family) were brought up together. Their mother was absent for almost a year (1664–65) during a long convalescent holiday in Italy, but she corresponded regularly with her sons’ governess and took a great interest in her sons’ upbringing, even more so on her return. After Sophia’s tour she bore Ernest Augustus another four sons and a daughter. In her letters, Sophia describes George as a responsible, conscientious child who set an example to his younger brothers and sisters.  By 1675 George’s eldest uncle had died without issue, but his remaining two uncles had married, putting George’s inheritance in jeopardy as his uncles’ estates might pass to their own sons, should they have had any, instead of to George. George’s father took him hunting and riding, and introduced him to military matters; mindful of his uncertain future, Ernest Augustus took the fifteen-year-old George on campaign in the Franco-Dutch War with the deliberate purpose of testing and training his son in battle.  In 1679 another uncle died unexpectedly without sons and Ernest Augustus became reigning Duke of Calenberg-Göttingen, with his capital at Hanover. George’s surviving uncle, George William of Celle, had married his mistress in order to legitimise his only daughter, Sophia Dorothea of Celle, but looked unlikely to have any further children. Under Salic law, where inheritance of territory was restricted to the male line, the succession of George and his brothers to the territories of their father and uncle now seemed secure. In 1682, the family agreed to adopt the principle of primogeniture, meaning George would inherit all the territory and not have to share it with his brothers.

The same year, George married his first cousin, Sophia Dorothea of Celle, thereby securing additional incomes that would have been outside Salic laws requiring male inheritance. The marriage of state was arranged primarily as it ensured a healthy annual income and assisted the eventual unification of Hanover and Celle. His mother was at first against the marriage because she looked down on Sophia Dorothea’s mother (who was not of royal birth), and because she was concerned by Sophia Dorothea’s legitimated status. However, she was eventually won over by the advantages inherent in the marriage.  In 1683, George and his brother, Frederick Augustus, served in the Great Turkish War at the Battle of Vienna, and Sophia Dorothea bore George a son, George Augustus. The following year, Frederick Augustus was informed of the adoption of primogeniture, meaning he would no longer receive part of his father’s territory as he had expected. It led to a breach between father and son, and between the brothers, that lasted until Frederick Augustus’s death in battle in 1690. With the imminent formation of a single Hanoverian state, and the Hanoverians’ continuing contributions to the Empire’s wars, Ernest Augustus was made an Elector of the Holy Roman Empire in 1692. George’s prospects were now better than ever as the sole heir to his father’s electorate and his uncle’s duchy.  Sophia Dorothea had a second child, a daughter named after her, in 1687, but there were no other pregnancies. The couple became estranged—George preferred the company of his mistress, Melusine von der Schulenburg, by whom he had two daughters in 1692 and 1693; and Sophia Dorothea, meanwhile, had her own romance with the Swedish Count Philip Christoph von Königsmarck. Threatened with the scandal of an elopement, the Hanoverian court, including George’s brothers and mother, urged the lovers to desist, but to no avail. According to diplomatic sources from Hanover’s enemies, in July 1694 the Swedish count was killed, possibly with the connivance of George, and his body thrown into the river Leine weighted with stones. The murder was claimed to have been committed by four of Ernest Augustus’s courtiers, one of whom (Don Nicolò Montalbano) was paid the enormous sum of 150,000 thalers, which was about one hundred times the annual salary of the highest paid minister. Later rumours supposed that Königsmarck was hacked to pieces and buried beneath the Hanover palace floorboards. However, sources in Hanover itself, including Sophia, denied any knowledge of Königsmarck’s whereabouts.  George’s marriage to Sophia Dorothea was dissolved, not on the grounds that either of them had committed adultery, but on the grounds that Sophia Dorothea had abandoned her husband. With the concurrence of her father, George had Sophia Dorothea imprisoned in Ahlden House in her native Celle, where she stayed until she died more than thirty years later. She was denied access to her children and father, forbidden to remarry and only allowed to walk unaccompanied within the mansion courtyard. She was, however, endowed with an income, establishment, and servants, and was allowed to ride in a carriage outside her castle, albeit under supervision.

Ernest Augustus died on 23 January 1698 leaving all of his territories to George with the exception of the Prince-Bishopric of Osnabrück, an office he had held since 1661. George thus became Duke of Brunswick-Lüneburg (also known as Hanover, after its capital) as well as Archbannerbearer and a Prince-Elector of the Holy Roman Empire. His court in Hanover was graced by many cultural icons such as the mathematician and philosopher Gottfried Leibniz and the composers George Frideric Händel and Agostino Steffani.  Shortly after George’s accession to his paternal dukedom, Prince William, Duke of Gloucester, who was second-in-line to the English and Scottish thrones, died. By the terms of the English Act of Settlement 1701, George’s mother, Sophia, was designated as the heir to the English throne if the then reigning monarch (William III) and his sister-in-law, Princess Anne of Denmark (later Queen Anne) died without surviving issue. The succession was so designed because Sophia was the closest Protestant relative of the British Royal Family; fifty-six Catholic relations with superior hereditary claims were bypassed. The likelihood of any of them converting to Protestantism for the sake of the succession was remote; some had already refused.  In August 1701 George was invested with the Order of the Garter and, within six weeks, the nearest Catholic claimant to the throne of England, ex-King James II, died. William III died the following March and was succeeded by Anne. Sophia became heiress presumptive to the new Queen of England. Sophia was in her seventy-first year, older than Anne by thirty-five years, but she was very fit and healthy and invested time and energy in securing the succession either for herself or her son. However, it was George who understood the complexities of English politics and constitutional law, which required further acts in 1705 to naturalise Sophia and her heirs as English subjects, and to detail arrangements for the transfer of power through a Regency Council. In the same year, George’s surviving uncle died and he inherited further German dominions: the Principality of Lüneburg-Grubenhagen, centred at Celle.

Shortly after George’s accession in Hanover, the War of the Spanish Succession broke out. At issue was the right of Philip, the grandson of King Louis XIV of France, to succeed to the Spanish throne under the terms of King Charles II of Spain’s will. The Holy Roman Empire, the United Dutch Provinces, England, Hanover and many other German states opposed Philip’s right to succeed because they feared that the French House of Bourbon would become too powerful if it also controlled Spain. As part of the war effort, George invaded his neighbouring state, Brunswick-Wolfenbüttel, which was pro-French, writing out some of the battle orders himself. The invasion succeeded with few lives lost. As a reward, the prior Hanoverian annexation of the Duchy of Saxe-Lauenburg by George’s uncle was recognised by the British and Dutch.  In 1706, the Elector of Bavaria was deprived of his offices and titles for siding with Louis against the Empire. The following year, George was invested as an Imperial Field Marshal with command of the imperial army stationed along the Rhine. His tenure was not altogether successful, partly because he was deceived by his ally, the Duke of Marlborough, into a diversionary attack, and partly because Emperor Joseph I appropriated the funds necessary for George’s campaign for his own use. Despite this, the German princes thought that he had acquitted himself well. In 1708 they formally confirmed George’s position as a Prince-Elector in recognition of, or because of, his service. George did not hold Marlborough’s actions against him which he understood were part of a plan to lure French forces from the main attack.  In 1709, George resigned as field marshal, never to go on active service again. In 1710, he was granted the dignity of Archtreasurer of the Empire, an office formerly held by the Elector Palatine—the absence of the Elector of Bavaria allowed a reshuffling of offices. The death of the Emperor in 1711 threatened to destroy the balance of power in the opposite direction, so the war ended in 1713 with the ratification of the Treaty of Utrecht. Philip was allowed to succeed to the Spanish throne but was removed from the line of succession to the French throne, and the Elector of Bavaria was restored.

Though both England and Scotland recognised Anne as their Queen, only the English Parliament had settled on Sophia, Electress of Hanover, as the heir. The Parliament of Scotland had not formally settled the succession question for the Scottish throne. In 1703, the Estates passed a bill that declared that their selection for Queen Anne’s successor would not be the same individual as the successor to the English throne, unless England granted full freedom of trade to Scottish merchants in England and its colonies. At first Royal Assent was withheld, but the following year Anne capitulated to the wishes of the Estates and assent was granted to the bill, which became the Act of Security 1704. In response the English Parliament passed measures which threatened to restrict Anglo-Scottish trade and cripple the Scottish economy if the Estates did not agree to the Hanoverian succession. Eventually, in 1707, both Parliaments agreed on an Act of Union which united England and Scotland into a single political entity, the Kingdom of Great Britain, and established the rules of succession as laid down by the Act of Settlement 1701. The union created the largest free trade area in eighteenth-century Europe.

Whig politicians believed Parliament had the right to determine the succession, and bestow it on the nearest Protestant relation of the Queen, while many Tories were more inclined to believe in the hereditary right of the Stuarts. In 1710, George announced that he would succeed in Britain by hereditary right, as the right had only been removed from the Catholic Stuarts, and he retained it. “This declaration was meant to scotch any Whig interpretation that parliament had given him the kingdom [and] … convince the Tories that he was no usurper.”  George’s mother, the Electress Sophia, died on 28 May 1714 at the age of 83. She had collapsed in the gardens at Herrenhausen after rushing to shelter from a shower of rain. George was now Queen Anne’s direct heir. He swiftly revised the membership of the Regency Council that would take power after Anne’s death, as it was known that Anne’s health was failing and politicians in Britain were jostling for power. She suffered a stroke, which left her unable to speak, and died on 1 August 1714. The list of regents was opened, the members sworn in, and George was proclaimed King of Great Britain and Ireland.  Partly due to contrary winds, which kept him in The Hague awaiting passage, he did not arrive in Britain until 18 September. George was crowned at Westminster Abbey on 20 October. His coronation was accompanied by rioting in over twenty towns in England.  George mainly lived in Great Britain after 1714 though he visited his home in Hanover in 1716, 1719, 1720, 1723 and 1725; in total George spent about one fifth of his reign as King in Germany. A clause in the Act of Settlement that forbade the British monarch from leaving the country without Parliament’s permission was unanimously repealed in 1716. During all but the first of the King’s absences power was vested in a Regency Council rather than his son, George Augustus, Prince of Wales.

Within a year of George’s accession the Whigs won an overwhelming victory in the general election of 1715. Several members of the defeated Tory Party sympathised with the Jacobites, and some disgruntled Tories sided with a Jacobite rebellion, which became known as “The Fifteen”. The Jacobites sought to replace George with Anne’s Roman Catholic half-brother, James Stuart (called “James III and VIII” by his supporters and “the Pretender” by his opponents). James’s supporters, led by Lord Mar, an embittered Scottish nobleman who had previously supported the “Glorious Revolution”, instigated rebellion in Scotland where support for Jacobitism was stronger than in England. “The Fifteen”, however, was a dismal failure; Lord Mar’s battle plans were poor, and James arrived late with too little money and too few arms. By the end of the year the rebellion had all but collapsed. In February 1716, faced with impending defeat, James and Lord Mar fled to France. After the rebellion was defeated, although there were some executions and forfeitures, George acted to moderate the Government’s response, showed leniency, and spent the income from the forfeited estates on schools for Scotland and paying off part of the national debt.

George’s distrust of the Tories aided the passing of power to the Whigs. Whig dominance would grow to be so great under George that the Tories would not return to power for another half-century. After the election, the Whig-dominated Parliament passed the Septennial Act 1715, which extended the maximum duration of Parliament to seven years (although it could be dissolved earlier by the Sovereign). Thus Whigs already in power could remain in such a position for a greater period of time.  After his accession in Great Britain, George’s relationship with his son (which had always been poor) worsened. George Augustus, Prince of Wales, encouraged opposition to his father’s policies, including measures designed to increase religious freedom in Britain and expand Hanover’s German territories at the expense of Sweden. In 1717 the birth of a grandson led to a major quarrel between George and the Prince of Wales. The King, supposedly following custom, appointed the Lord Chamberlain, the Duke of Newcastle, as one of the baptismal sponsors of the child. The King was angered when the Prince of Wales, disliking Newcastle, verbally insulted the Duke at the christening, which the Duke misunderstood as a challenge to a duel. The Prince was told to leave the royal residence, St. James’s Palace. The Prince’s new home, Leicester House, became a meeting place for the King’s political opponents. George and his son were later reconciled at the insistence of Robert Walpole and the desire of the Princess of Wales, who had moved out with her husband but missed her children who had been left in the care of the King. However, following the quarrel at the baptism, father and son would never again be on cordial terms.

George was active in directing British foreign policy during his early reign. In 1717 he contributed to the creation of the Triple Alliance, an anti-Spanish league composed of Great Britain, France and the United Provinces. In 1718 the Holy Roman Empire was added to the body which became known as the Quadruple Alliance. The subsequent War of the Quadruple Alliance involved the same issue as the War of the Spanish Succession. The Treaty of Utrecht (1713) had recognised the grandson of King Louis XIV of France, Philip, as the King of Spain on the condition that he gave up his rights to succeed to the French throne. Upon the death of Louis XIV in 1715, however, Philip sought to overturn the treaty.  Spain supported a Jacobite-led invasion of Scotland in 1719 but stormy seas allowed only about three hundred Spanish troops to arrive in Scotland. A base was established at Eilean Donan Castle on the west Scottish coast in April, only for it to be destroyed by British ships a month later. Attempts by the Jacobites to recruit Scottish clansmen yielded a fighting force of only about a thousand men. The Jacobites were poorly equipped, and were easily defeated by British artillery at the Battle of Glen Shiel. The clansmen dispersed into the Highlands, and the Spaniards surrendered. The invasion never posed any serious threat to George’s government. With the French this time fighting against him in the War, Philip’s armies fared poorly. As a result, the Spanish and French thrones remained separate. Simultaneously Hanover gained from the resolution of the Great Northern War which had been caused by rivalry between Sweden and Russia for control of the Baltic. The Swedish territories of Bremen and Verden were ceded to Hanover in 1719, with Hanover paying Sweden monetary compensation for the loss of territory.

As requested by Walpole, George revived the Order of the Bath in 1725 which enabled Walpole to reward or gain political supporters by offering them the honour. Walpole became extremely powerful and was largely able to appoint ministers of his own choosing. Unlike his predecessor, Queen Anne, George rarely attended meetings of the cabinet; most of his communications were in private, and he only exercised substantial influence with respect to British foreign policy. With the aid of Lord Townshend, he arranged for the ratification by Great Britain, France and Prussia of the Treaty of Hanover, which was designed to counterbalance the Austro-Spanish Treaty of Vienna and protect British trade.  George, although increasingly reliant on Walpole, could still have replaced his ministers at will. Walpole was actually afraid of being removed from office towards the end of George I’s reign, but such fears were put to an end when George died during his sixth trip to his native Hanover since his accession as king. He suffered a stroke on the road between Delden and Nordhorn on 9 June 1727, and was taken by carriage to the Prince-Bishop’s palace at Osnabrück where he died in the early hours of 11 June 1727. He was buried in the chapel of Leine Castle but his remains were moved to the chapel at Herrenhausen after World War II.  George was succeeded by his son, George Augustus, who took the throne as George II. It was widely assumed, even by Walpole for a time, that George II planned to remove Walpole from office but was prevented from doing so by his queen, Caroline of Ansbach. However, Walpole commanded a substantial majority in Parliament and George II had little choice but to retain him or risk ministerial instability.[81] In subsequent reigns the power of the prime minister increased further at the expense of the power of the sovereign.