[7]: 385 Tipu Sultan planned the invasion of Travancore for many years, and he was especially concerned with the Nedumkotta fortifications, which had prevented his father Hyder Ali from annexing the kingdom.

[8] Both Tipu Sultan and Governor John Holland of Madras objected to these purchases because the forts, though they had long been in Dutch possession, were in the Kingdom of Cochin[7]: 391 Kesava Pillai was appointed Commander-in-Chief of the Travancore Army.

[7]: 393 A number of Mysorean soldiers encroached into Travancorean jungles, ostensibly to apprehend fugitives, and came under fire when discovered by patrols of the Paravoor Battalion of the Travancore Army.

[5][page needed][7][8] On 28 December 1789, Mysorean troops attacked the eastern part of the Travancori lines and captured the ramparts as the Travancoreans retreated, but were eventually stopped when the Travancorean force of 800 Nairs made a stand with the help of a 6-pounder gun;[5][page needed][8] At first, the Mysoreans overpowered three batteries of the lines.

Travancori reinforcements arrived during the four-hour battle, but the panic had now become general and the retreating Mysorean soldiers were borne on to the ditch, while others were forced into it by the mass which pressed them from behind.

Those Mysoreans who had not yet been trampled by their horses while retreating to the point from which they had invaded the lines found that the sacks with cotton, used for filling up the ditch, when they set up as well as some powder barrels, had caught fire.

The Madras Government was duly informed of the Sultan’s position, and the Maha Rajah received assurances from the British Governor of assistance in the event of invasion.

[5]: 166  The wall resisted Mysorean fire for nearly a month and on 15 April, a practicable breach of three-quarters of a mile in length was effected.

The whole line thus fell into the hands of the Sultan, together with 200 pieces of cannon of various sizes and metal and an immense quantity of ammunition and other warlike stores, which were forwarded to Coimbatore as trophies.

The Sultan's first object was to destroy the Travancore lines and fill up the ditch, and so he took a pickaxe himself and set an example which was followed by every one present and the demolition of the wall was completed by his army.

[8] The south-west monsoon broke out with unusual severity and Aluva river, a stream which usually rises after a few showers, filled and overflowed its banks, causing Tipu's army great inconvenience and rendering their march almost impossible.

The current, during the freshes in the river was so strong, that even the permanent residents of the adjacent villages find difficulty in crossing it at that time.

As the country around is mostly intersected by numerous rivers and streams, and intermixed with large paddy fields submerged under water at this season, Tipu and his army were surprised at a scene which they had seldom witnessed before, and were bewildered by their critical situation.

[8] Kesava Pillai, after leaving Paravoor, strengthened the garrison at every military station, both at the sea beach and at Arookutty and other places, erected stockades at every backwater passage, and fortified the line and batteries between Kumarakam and the Kundoor hills at Poonjar.

He informed the Maha Raja that Tipu Sultan's progress from Aluva was totally impeded by the rain, and any attempt to march with his army from Aluva up-country, would be impeded by the natural defences of the country and that the line between Kumarakam and Kundoor hills had been strongly barricaded while a regular militia lined the hills and the sea.

While Tipu was in his uncomfortable encampment at Aluva, intelligence of the commencement of hostilities and the assembling of a large East India Company force at Trichinopoly reached him.