George I
George I was the king of Great Britain and Ireland, and elector of Hanover.
History
George was the eldest son of Ernest Augustus, duke of Brunswick-Lüneburg, and Sophia. Sophia was a granddaughter of James I.
Per the Act of Settlement of 1701, Catholics could not succeed to the English throne. Therefore when Anne died in 1714, the crown passed over the Jacobite claim to George. This established the Hanoverian dynasty and brought England into personal union with Hanover, and therefore into the Holy Roman Empire.
In the early years of his reign, George held significant power in British governance and politics. He appointed a new Whig government. He entirely reversed the foreign policies that had been consistent across the reigns of William, Mary, and Anne before him. This became known as the Hanoverian foreign policy. He appointed Stanhope to implement his vision.
Just years after the War of Spanish Succession contained French influence, George negotiated the Anglo-French Alliance with the infant Louis XV and his regent Philippe II, Duke of Orleans.
George expanded this into the Triple Alliance, and finally the Quadruple Alliance, by pulling in the Dutch and Austrians. George then led England into the War of the Quadruple Alliance.
George brought England into Hanover's part of the Great Northern War. Note that William had actually intervened at the war's inception to defend Sweden, and note that Anne had remained neutral. The Treaty of Stockholm in 1719 led to Hanover (and England) making peace with Sweden, and subsequently assisting against Russian invasions that continued until 1721.
Domestically though, a Whig Split emerged by 1717. Walpole and Townshend lead an effective opposition.
The split was mended after a few years; importantly though this coincided with the South Seas Bubble. The South Seas Company had been established by Anne's government led by Harley. The company had been granted a monopoly on slave trade in the southern Pacific and Atlantic, which attracted interest from private finance. The government sold shares in the company to buy back public debt, effectively consolidating the national debt (which had ballooned as a result of the War of Spanish Succession) into a chartered company. The company was already failing to turn a profit and post payments upon George's succession, but he (and many prominent Whigs) held significant stakes in the company--so they doubled down on the scheme and secured further financing. Ultimately though the bubble collapsed in 1720.
Because George had removed all Tories from the company's board upon succession, and because all oppositional Whigs were similarly removed during the split, the scandal was entirely contained to George's loyal ministers. With the split having just been mended, Walpole quickly emerged as the dominant remaining minister. From this point on, he is considered to be the first prime minister. He significantly restrained the Hanoverian foreign policy, and began a gradual movement of domestic powers to the House of Commons.
George died in 1727 and was succeeded by his son, George II. Walpole remained the head of government across the transition of power, reinforcing his role as de facto head of state.