Maratha invasions of Bengal
The Maratha invasions of Bengal (1741–1751), also known as the Maratha expeditions in Bengal, were the frequent invasions by the Maratha forces in the Bengal Subah (Bengal, Bihar, parts of modern Orissa), after their successful campaign in the Carnatic region at the Battle of Trichinopoly. The leader of the expedition was Maratha Maharaja Raghoji Bhonsle of Nagpur. The Marathas invaded Bengal five times from August 1741 to May 1751, which caused widespread economic losses in the Bengal Subah. Invasions of Bengal 

From 1741 to 1751, the Marathas under Raghuji Bhonsle invaded Bengal six times. The first one in 1741, as also the third in 1744, was led by Raghuji's general Pandit Bhaskar Ram Kolhatkar or Bhaskar Pandit. The second in 1742 and the fourth in 1745 were led by Raghuji himself. The fifth in 1747 and the sixth in 1748 were undertaken by Janoji and Sabaji respectively. These invasions caused heavy destruction in the armies of the Nawab of Bengal. Nawab Alivardi Khan was successful in repelling all the invasions. In 1743 two Maratha Armies invaded - one belonged to Raghuji Bhosle, the other to Balaji Rao. To persuade the latter to withdraw, Alivardi Khan was obliged to pay him a subsidy and promise to pay him chauth (tax) in the future. The continuous conflict took a heavy toll on the population of Bengal. First invasion (1741) 
After the ascension of Alivardi Khan as the Nawab of Bengal, the provincial governor of Orissa, Lutfullah Tabrizi Rustam Jung, more commonly known as Murshid Quli II, revolted against him. The revolt was crushed by Alivardi in March 1741, but Murshid Quli II escaped with his family and took shelter of Raghuji Bhonsle, the Maratha ruler of Nagpur. Raghuji agreed to assist Murshid Quli II in regaining Orissa. Murshid Quli II's son-in-law Mirza Baker, assisted by Maratha troops and the rebel forces of Orissa (who were dissatisfied with the governor of Orissa), invaded Orissa in August 1741. Orissa's governor, Syed Ahmed Khan (a nephew of Alivardi Khan), was defeated and captured along with his family. Hearing of this, Alivardi rushed to Orissa and Alivardi's commander Mir Jafar freed Syed Ahmed and his family. Alivardi regained control of Orissa and returned to Murshidabad. The Marathas retook Orissa in 1749. End of hostilities 

In 1751, the Marathas signed a peace treaty with the Nawab of Bengal. The territories beyond the Subarnarekha River were now ceded to the Marathas, according to which, Mir Habib (a former courtier of Alivardi Khan, who had defected to the Marathas) was made provincial governor of Orissa under nominal control of the Nawab of Bengal. It made The Nawab of Bengal a tributary to the Marathas who agreed to pay Rs. 1.2 million annually as the chauth of Bengal and Bihar, and the Marathas agreed not to invade Bengal again. The Nawab of Bengal also paid Rs. 3.2 million to the Marathas, towards the arrears of chauth for the preceding years. The chauth was paid annually by the Nawab of Bengal up to 1758, until the East India Company seized control of Bengal. 