Muhammad Ali Khan Wallajah, or Muhammed Ali, Wallajah (7 July 1717 – 13 October 1795), was the Nawab of Arcot in India and an ally of the British East India Company. Muhammad Ali Khan Wallajah was born to Anwaruddin Muhammed Khan, by his second wife, Fakhr un-nisa Begum Sahiba, a niece of Sayyid Ali Khan Safavi ul-Mosawi of Persia, sometime Naib suba of Trichonopoly, on 7 July 1717 at Delhi. Muhammed Ali Khan Wallajah the Nawab of Arcot often referred to himself as the Subedar of the Carnatic in his letters and correspondence with the then Mughal Emperor Shah Alam II.

 

 Muhammad Ali Khan Wallajah was granted the titles of "Siraj ud-Daula", Anwar ud-din Khan Bahadur, and Dilawar Jang, together with the Subadarship of the Carnatic Payeen Ghaut and a mensab of 5,000 zat and 5,000 sowar, the Mahi Maratib, Naubat, etc. by Imperial firman on 5 April 1750. 

 

 He joined forces with Nasir Jung and the British in opposing Chanda Sahib, the French nominee for the Subadarship. He was defeated by the French at Gingee in December 1750, and fled to Trichnopoly for a second time. He received an Imperial firman confirming his possession of the Carnatic and appointing him as Naib to Viceroy of the Deccan, 21 January 1751. 

 

Raised to the titles of Walla Jah and Sahib us-Saif wal-qalam Mudabbir-i-Umur-i-'Alam Farzand-i-'Aziz-az Jan by Emperor Shah Alam II in 1760, he was recognised by the Treaty of Paris as an independent ruler in 1763 and by the Emperor of Delhi 26 August 1765. 

 

 Sir John Macpherson, writing to Lord Macartney in November 1781 declared, "I love the old man...mind me to my old Nabob. I have been sending him sheep and bags of rice by every ship. It is more than he did for me when I was fighting his battles." 

 

The Nawab was an ally of the British East India Company, but also harboured great ambitions of power in the South Indian arena, where Hyder Ali of the Mysore, the Marathas, and the Nizam of Hyderabad were constant rivals. The Nawab could also be unpredictable and devious, and his breach of promise in failing to surrender Tiruchirappalli to Hyder Ali in 1751 was at the root of many confrontations between Hyder Ali and the British. When Hyder Ali swept into the Carnatic towards Arcot on 23 July 1780, with an army estimated at 86–100,000 men, it was not the Nawab, however, but the British who had provoked Hyder Ali's wrath, by seizing the French port of Mahé which was under his protection. Much of the ensuing war was fought on the Nawab's territory. 

 

 For the defence of his territory, the Nawab paid the British 400,000 pagodas per annum (about £160,000) and 10 out of the 21 battalions of the Madras army were posted to garrison his forts. The British derived income from his jagirs (land grants). 

 

 The Nawobs of Arcot, the rulers of the kingdom in the Carnatic region of Tamil Nadu were reasonably rich and had a large collection of jewelry and precious stones. In 1777, the ruler presented one of the valuable diamonds then to Queen Charlotte as a token of the Nawob's loyalty and allegiance - a sort of "Nazrana" in Urdu to the English Crown. It was an expression of gratitude to the British company for their timely military assistance against the French aggression backed by their local Indian allies during their most tested period of their rule. However, the British were ungrateful to the generous ruler Nawob Muhammad Ali Khan Wala-Jah (1752 to 1795) when he was unable to pay heavy debts - the annual fee of military help - £160,000.00 incurred as a result of military assistance provided by the British and for the restoration of throne and kingdom from Chanda Sahib and his French alley. To compensate unpaid heavy debts, the British East India Company, under duress, took over the kingdom of the Carnatic, forcing the rich Nawob royal family to become a mere titular ruler, receiving one-fifth of the total revenue of the State for the maintenance of his palaces. The British cunningly shared the major portion of the pie. A diabolical diplomacy they had been following since the take over of Bengal in the late 1700s.