The Duke of Newcastle was born Thomas Pelham-Hobbes in 1693. He was the heir of Thomas, First Baron Pelham and his Lady Grace Holles. He was educated at Westminster and Clare College, Cambridge, which he left without a degree. In 1712, he became the Second Baron Pelham, inheriting his father’s estate and peerage, becoming Lord Pelham.

John Holles, the Duke of Newcastle, Pelham’s uncle, made young Thomas his heir. In doing so, the old Duke not only overlooked his sisters, his own daughter, and several nephews, but also created the circumstances that would give rise to one of the most powerful politicians in British history. In 1711, Thomas Pelham had inherited his uncle’s estates (after some legal haggling), changing his name to Thomas Pelham-Holles as part of the inheritance agreement. He became the Duke of Newcastle in 1715.

Taking his seat in the Lords in August 1714, Newcastle soon decided to follow a political path. He ingratiated himself with King George I by arranging for a cheering crowd on the day of his proclamation. He began to associate with the Whig faction, and he quickly joined the Kit Kat Club and Hannover Club, making friends with many important Whigs. As Lord-Lieutenant of Middlesex and Nottingham, he played a part in the repression of Jacobitism.

In 1717, Newcastle married Lady Harriet Godolphin, whose grandfathers were Lord Godolphin and the Duke of Marlborough, once again raising his social status.  Now, one of the most powerful and best-connected Whig politicians in the country, Newcastle had considerable lands, and controlled about 15 constituencies. He was appointed Lord Chamberlain in 1717.

During the 1720s, Newcastle became a supporter of Robert Walpole, and in 1724 he was rewarded with an appointment to the position of Southern Secretary. By the 1730s, Newcastle and his half-brother Henry Pelham, who was Paymaster General, were some of Walpole’s closest allies – with Newcastle now the government’s chief spokesman in the House of Lords.

Newcastle’s political career survived the fall of Walpole, and he continued as Southern Secretary until 1748, before changing to the Northern Department until 1754 (totalling three full decades in Cabinet). In 1743, Henry Pelham became Prime Minister, and Newcastle effectively served his younger half-brother. At the end of the War of the Austrian Succession, he sought a new peace in Europe based on a strong alliance with Austria, which was dubbed the ‘Newcastle System’.

In 1754, Henry Pelham died, leaving the Duke devastated. The relationship had not always been easy, with Newcastle sometimes irritated by his brother’s superior position, but ultimately they had worked well together. In Pelham’s absence, George II asked Newcastle to become Prime Minister, and he accepted the position.

In Spring 1754, Newcastle oversaw an election, winning a large majority. He had hoped to pass some financial reforms, but his government’s priorities were soon dominated by tensions with France. In 1754, a party of American colonists led by a young colonial officer named George Washington, had been defeated by the French on the Pennsylvania frontier. The following year, a British expedition to reverse the situation and gain control of the Ohio country was destroyed by French forces and their native allies. France and Britain were still technically at peace, but a full war now seemed inevitable.

In May 1756, that war came, and the news worsened, with a major defeat on the island of Menorca. Newcastle arranged the trial and execution of Admiral Byng for cowardice after the defeat.

The reality was that while Newcastle was a master of political organisation, negotiation, and patronage, he was not an inspiring war leader. He had little grasp of geography or strategy and worked better as a subordinate.

In the Commons, William Pitt severely criticised Newcastle’s faltering ministry. Meanwhile, in Europe, France and Austria concluded an alliance, while Britain’s ally Prussia attacked Austria in the summer. War on the continent had now broken out and Britain had no choice but to support the isolated Prussians with subsidies.

In October 1756, Henry Fox (who led the Commons) resigned and joined the opposition. Newcastle had no choice but to resign himself and was soon replaced by 1756 by the Duke of Devonshire. But Devonshire’s ministry did not last.

In June 1757, George II invited Newcastle back to become First Lord of the Treasury, now in alliance with his erstwhile critic, William Pitt. Horace Walpole wrote that the arrangement was that ‘Mr Pitt does everything, the duke gives everything.’ Over the years that followed, Pitt directed strategy and commanded parliamentary support, while Newcastle supplied the money, ran the Treasury, and liaised with the king.

Over 1758-60, their efforts were rewarded with success. British arms triumphed in North America, India, at sea, and in Germany. The year 1759 became known as ‘the Year of Victories’.

Personally, Newcastle was fussy and neurotic, earning the nickname ‘Hubble-Bubble’. Once, during the Seven Years War, he took to bed, and when William Pitt arrived to discuss naval strategy, Newcastle asked Pitt to occupy an adjacent bed so they might have their discussion.

The government frayed from 1760, when George II died and was replaced by George III. The new King had a greater interest in running politics, disliked Newcastle, and was keen to promote his favourite, Lord Bute. Moreover, the victories of 1759 and 1760 had effectively won the war for Britain, and many now believed it was time to make peace.

In October 1761, Pitt the Elder resigned because the ministry refused to countenance a pre-emptive strike against Spain. With him went the government’s energy, and Newcastle himself resigned in May 1762, refusing a pension from George III.

And yet, Newcastle could not give up politics and he went into opposition. In 1765, he briefly became Lord Privy Seal in Lord Rockingham’s government.

Newcastle died in November 1768.