The Commander in Chief of the Mysore Calicut Province, Sirdar Ali, took siege of the British Military Barrack of Thalassery for 18 months.

The siege continued until reinforcements from Bombay under the command of Major Abington attacked the Mysore army and defeated them.

[1][2] Tellicherry (Thalassery) rose to become a fortified coastal harbor and major town under English East India Company control.

Hyder's conquest of Tellicherry would have been a big blow to British naval position in waters of Peninsular India.

So in order to block flow of guns and ammunition to rebellious Rajahs and chiefs of Malabar as well as to cripple British naval power, Hyder Ali decided to conquer Tellicherry as part of his larger plan to oust British from South India.

[5] British and their ally Kottayam contingent fought a desperate defense for months – each assault of the Mysore army was repelled and the siege went on till 1782.