Dharma Raja Karthika Thirunal Rama Varma(‘ധര്‍മ്മ രാജ‘ കാര്‍ത്തിക തിരുനാള്‍ രാ‍മവര്‍മ്മ) was the Maharajah of Travancore from 1758 -1798. He succeeded his uncle Marthanda Varma, who is credited with the title of "maker of modern Travancore". During his reign Dharma Raja not only retained all the territories his predecessor had gained but administered the kingdom with success. He was addressed as Dharma Raja on account of his strict adherence to Dharma Sastra, the principles of justice by providing asylum to the thousands of Hindus fleeing Malabar during the religious and military onslaught of Tipu Sultan.

RAma Varma was born in 1724 AD as the son of the Senior Rani of Attingal with her husband Prince Kerala Varma Koil Thampuran of the Kilimanoor palace. He had a brother Prince Makayiram Thirunal, grandfather of Irayimman Thampi, who predeceased him. His mother was adopted from the royal house of Kolathunad in 1718 by the then King of Venad into the Travancore Royal Family. He was born into a time of political turmoil caused by the refractory Lords, the Ettuveetil Pillamar as also enemies of Venad such as the Rajah of Kayamkulam. When Karthika Thirunal was only four years of age, in 1728, his father died foiling an assassination bid by the Kayamkulam Rajah, when the prince along with his parents were traveling from Haripad to the domains of the Vanjipuzha Thampuran, a Brahmin chief, at Budhanur . As he grew up he took pat actively in the military conquests of his uncle Maharajah Marthanda Varma and assisted him in establishing the modern state of Travancore by annexing kingdom after kingdom till Cochin to Venad.

Succession and Initial Career
With the death of Marthanda Varma in 1758, his nephew Karthika Thirunal Rama Varma succeeded to the Travancore musnud. With the able services of the Dalawa Ayyapan Marthanda Pillai, Karthika Thirunal began his reign. By now due to the efforts of his predecessor Travancore had gained the reputation of the most powerful state in Kerala and hence many of the neighboring chiefs wished to execute treaties with the Maharajah. Accordingly in 1762 AD the Rajah of Cochin sent his nephew to sign a treaty with Travancore. In the same year, a few months later, the Rajah himself visited Travancore along with his minister, the Paliath Achan, and signed a treaty with Travancore and secured aid to free his territories from the control of the Zamorin of Calicut. Accordingly the armies of Travancore under Ayyapan Marthanda Pillai and Eustachius De Lannoy, the Travancore General, attacked the Zamorin's camp in Cochin state and forced him to retreat into his own territories. The Travancore army then contemplated attacking the Zamorin but the latter deputed an express messenger to the Maharajah asking him to refrain from attacking his kingdom. The request was complied with and in 1763 the Zamorin signed a treaty of friendship and reimbursed Travancore with the expenses of the war. Besides, the little kingdoms of Parur and Alangad were also annexed to Travancore after pensioning off the ruling families. The Maharajah also continued with the fortifications known as Nedumkotta to protect the northern frontiers of Travancore from a contemplated attack by Hyder Ali of Mysore. In fact the Dutch records state that the Maharajah deliberately refrained from annexing Cochin and the Zamorins' kingdom so as to maintain a buffer between his kingdom and Mysore. Certain territorial disputes arose during this period between Travancore and the Nawab of Arcot which were eventually settled, though the Maharajah had to part with large sums of money and some territories.

Dharma Raja and Hyder Ali
Hyder Ali had usurped the throne of Mysore and was keen to invade and bring the little kingdoms of Malabar and Travancore under his sway. As early as 1756 he had invaded Malabar at the instance of the ruler of Palghat but had to return due to troubles in his own kingdom. In 1766 he invaded Malabar a second time. The Rajah of Kolathunad fled to Travancore while the Zamorin after hastening his family's departure to Travancore committed suicide in his own palace. Hyder Ali also started treaty negotiations with the Dutch, who since their defeat in the Battle of Colachel had been in awe of the Travancore Maharajah and kept him informed of all developments. Soon rumors of a proposed invasion of Travancore started developing after Travancore refused to stop the construction of Nedumkotta which passed from the vicinity of the Dutch, besides having given refuge to the political foes of Hyder Ali. Hyder Ali asked both Cochin and Travancore to pay him tributes. While the Cochin Rajah agreed, Karthika Thirunal of Travancore replied stating that it was "neither to please him nor in accordance with his advice that the invasion of Malabar was undertaken". But he stated that if Hyder Ali retracted from Malabar and reinstated the Kolathunad and Calicut kings back to their kingdoms, he would be pleased to provide a certain sum. This was taken as Hyder Ali as a threat but before he could plan an attack on Travancore, he had to return to Mysore .

Dharma Raja and Tipu Sultan
In 1788 Tipu Sultan, son and successor of Hyder Ali took up his father's idea of subjugating Malabar and Travancore. He laid waste Malabar, enforced the rule of "cap or sword" i.e. wither converting to Islam or immediate execution, forcing the royal families and large numbers of Brahmin and Nair families to flee to Travancore where they were received and treated hospitably by the Maharajah, who now came to be known as Dharma Raja on account of his protecting Hindus and the Hindu faith. Tipu Sultan now demanded that the Rajah of Cochin who had accepted the status of a vassal to claim Alangad and Parur so as to provide him with a pretext to invade Travancore, however the Rajah diplomatically saved himself from this embarrassment. Tipu then sent his envoys to Travancore with a Khareeta wherein he stated that "I have learnt..that you desire to cultivate friendship with our Sircar..". The Travancore Maharajah had received Tipu's envoys in the presence of a British representative, which was taken to badly by the Mysore Sultan. The Maharajah also secured a force from the British, apprehending an attack from Tipu Sultan. Finally in 1789, taking the pretext that Nedumkotta passed illegally through the Cochin (his vassal state) territories, Tipu Sultan gathered his entire force in Malabar and marched to invade Travancore .
They reached the Nedumkotta line which protected Travancore's northern frontier and slowly started demolishing activities. But a group of merely twenty Travancore soldiers managed to change the course of events by opening fire on the 14000 Mysore infantry from a close cover. The commanding officer was killed and the entire army fell into disarray. Each and every advancing corp was thrown into confusion and Tipu Sultan himself was carried away by the crowd. His palanquin, seals, rings, sword and other personal ornaments fell into the hands of the Travancore armies under the Dewan Raja Kesavadas Pillai. Thus Tipu's first attack was repelled by the successful Travancore forces. The battle was particularly significant because it was only twenty Travancore Nairs who kept the Sultan's army confused by their attack.
In the following weeks Tipu Sultan, stung by his defeat, complained to the British at Madras that it was Travancore which had taken the offensive and thus the battle had been fought. Finally Tipu attacked the Nedumkotta again. For nearly a month the Travancore army under the protection of the Nedumkotta lines managed to defend the state. However finally a breach, three quarters of a mile, was effected and the Mysore army entered Travancore. Soon the entire Nedumkotta line fell into the hands of Tipu Sultan with large amounts of ammunition and guns. The British forces sent to assist Travancore did not provide aid to Travancore but remained passive spectators, much to the despair of the Maharajah. Tipu's army now devastated the whole of northern Travancore and reached Alwaye and camped therein. Hindu temples were destroyed and the subjects fled to the forests. the entire country was laid waste with fire and sword. Even Christians were not spared.
Raja Kesavadas Pillai, the Dewan, now raised batteries of the Travancore army at various places and surrounded them with deep ditches and prepared for another battle with Tipu Sultan. The Sultan and his army now moved to a place where the Travancore army had built a wall across a river obstructing the water, leaving the river bed dry. In spite of the warnings of some of his generals, Tipu Sultan decided to wage a battle here at night, certain of his superior numbers. When the battle did begin, the Travancore army broke down the wall, leaving the water onto the Mysore forces with great force that a large number of Tipu's soldiers were killed by the sudden flood. The remaining forces were defeated by a sudden attack of Travancore under the Dewan and an able general known as Kali Kutty Pillai. Although the Sultan was once again defeated and prevented from gaining any more ground in Travancore, the Dewan increased the garrison of the forts and maintained a military force ready for battle in any case.
Meanwhile the Governor General of the British removed the Governor of Madras, Mr. Holland, from that post on hearing that the British had not provided any aid to Travancore in the battle. The new Governor mobilized the British forces stationed in Travancore to support the Maharajah. Hearing of this Tipu Sultan decided to retreat from Travancore and Malabar to his own kingdom to avoid war with the British. But war did occur in which Travancore provided its forces to the British which eventually led to the defeat of Tipu Sultan and in 1792 the Treaty of Seringapatanam was signed. .
Treaty with the British
Following the Treaty of Seringapatanam, the British demanded large sums from Travancore for the expenses of the war, which although the Maharajah did not subscribe to, thought it prudent to pay as he was not in a military position to oppose the English. A Subsidiary Alliance was made between Travancore and the British by which and subsidiary force was to be stationed in Travancore. Besides the Maharajah was also to help the British during times of need

Communications were opened to facilitate trade and business in the state by the Maharajah under the able Dewanship of Rajah Kesavadas.Ports were improved and various new products were exported by Travancore during this reign. Ship building was also given importance and several developments in this regard took place.
Gold coins known as Anantharayan Fanam, Chinna Fanam and Ananthavarahan were minted in Travancore in addition to a large bullion of silver, coined as Chuckrams.
During wartime taxes were raised but after the payments to the British and overcoming wartime expenses, these taxes were remitted.
The capital at Trivandrum was developed and infrastructure like bridges and other public works such as canals for irrigation were constructed. Bazaars and shopping centers were started for the benefit of the people.
The fortifications were bettered as also the ammunition and weapon manufacture was undertaken with greater vigor, particularly the manufacturing of guns. Palaces in different parts of the country were developed and new ones built.
An interesting insight into the religious tolerance of the Maharajah is gained through a letter by Pope Clement XIV wherein His Holiness thanked the Maharajah for the kindness to the members of his church in Travancore.

Kathakali Playwright and Composer
As the composer of Kathakali Plays (attakadha). He set a systematic curriculum for teaching Kathakali. Being a good vocalist and scholar in music and dance, he composed excellent Kritis which have enriched Carnatic music. He was perhaps the first violinist from the royal family. He has to his credit nearly 150 compositions. It was with the advent of the Kathakali plays of Karthika Thirunal that many reforms were brought in Kathakali. Changes were implemented in the structure of plays and in their technique to be adopted during presentation. Priority was given for sringara padas.. The rule that each character should enter the stage with sringara padas was introduced by him. Katthi characters must enter by presenting pada in Padi raga. All his kathakali plays attained much popularity and fame on account of its technical superiority in stage presentation, variety and vividness of characters and the story. He has to his credit seven plays:
Panchali Svayamvaram,
Kalayanasougandhikam (Thekkan or southern style)

The Maharajah passed away on the 17th of February, 1798 at the age of seventy four after a long reign that was prosperous, save for the invasion of the kingdom by Tipu Sultan. He had maintained the sovereignty of Travancore and protected it from destruction by the superior Mysore forces. He maintained the friendship cultivated with the British by his uncle Marthanda Varma. More importantly, he came to be known as Dharma Raja due to the asylum he provided to the thousands of people from Malabar fleeing to escape forced proselytization by Tipu Sultan. So pleased were these subjects of Malabar that many families of kings and nobles stayed back in Travancore.
Karthika Thirunal Maharajah had four wives or Ammachis. His first wife was Panapillai Kali Amma Nagamani Amma from Vadasseri. His other three wives hailed from Thiruvattar, Arumana and Nagercoil. He constructed four Ammaveedus for his wives in Trivandrum in the last decade of the 18th century and these families are his descendants. The Maharajah's brother married from the Puthumana Ammaveedu and his grandson was the poet Irayimman Thampi. The Maharajah's descendant from Arumana Ammaveedu married Balarama Varma, his successor, and their descendant was the consort of Visakham Thirunal Maharajah.(This information is from "Thiruvananthapurathinte Eithihaasam")