Tipu Sultan was now determined to retaliate against Travancore. He remained in the vicinity of the northern frontier and concentrated a large army there of infantry, cavalry and artillery. 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. In the meantime, Travancore repaired its northern frontier line and concentrated all available troops there. Recruits were enlisted, and guns, stores and ammunition were stored in the arsenals. On 1 March 1790, 1,000 Travancore troops advanced onto Mysore territory, where they were stopped and pushed back with considerable losses by Mysorean troops.Tipu's artillery began on 6 March. Finding no perceptible effect on the wall, a few more batteries were erected close to the northern wall and the largest guns were mounted, which opened a destructive fire. On 9 April 1790, a similar attempt was made once again by 1,500 Travancore troops on Mysore territory, however, they were once again stopped by Mysorean troops and repulsed. 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 Travancore troops abandoned the
Travancore lines and retreated. Tipu Sultan took approximately 6,000 soldiers and advanced on the Travancore position. On 18 April 1790, Tipu arrived within one mile of
Cranganur and erected batteries. On 8 May he successfully occupied Cranganur. Soon Travancorean forces abandoned forts such as Ayicotta and Parur and retreated. A portion of Mysorean troops under de Lalée proceeded to
Kuriapilly, also abandoned by the Travancoreans. 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. While the warfare was going on, the two
East India Company regiments stationed at Aycottah and another brigade consisting of a European and two native regiments just landed from Bombay under
Colonel Hartlay at
Monambam and
Palliport remained passive spectators, saying that they had received no orders from the Governor of Madras to fight against the Sultan. 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. Tipu Sultan advanced as far as
Alwaye. 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. His army had no shelter, no dry place for parade, and all their ammunition and accoutrements got wet and the provisions became scanty.
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. All the responsible officers, both military and revenue, were posted and the divisional revenue authorities were directed to remain at intermediate stations and raise
irregular militia, armed with whatever weapon the people could get, such as bows, arrows, swords and cudgels. 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. The British Governor of Madras addressed
Dharma Raja, assuring him that preparations were in progress for attacking Tipu Sultan. 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. The Sultan needed to beat a precipitate retreat. The rivers were all full. The country was under water. Except boats, no other means of communication could be used in that part of the country at that time. Tipu Sultan divided his army into two portions and ordered one portion to retreat via
Chalakudy to
Trichoor and thence to
Palghat, and the other via
Cranganore and
Chavakkad to Palghat. ==Aftermath==