There is the mention of the Nayar pada, which was later, much later recreated as the Nayar Brigade under English officers. However, the beginnings of the English military systems were actually given by a Dutch military officer. Name: De Lannoy. He was a war prisoner of Marthanda Varma, who was asked by the king to create military wing on European (meaning Dutch/English) lines. See this quote:

The first, De Lannoy, commonly known in Travancore as the Valia Kappithan (Great Captain) was in the manner of an experiment entrusted with the organisation and drilling of a special regiment of sepoys this he did very successfully and to the satisfaction of the Maharajah. Several heroic stories are extant of the achievements of this particular regiment. De Lannoy was next made a Captain and entrusted with the construction of forts and the organisation of magazines and arsenals. He reorganised the whole army and disciplined it on European models, gave it a smart appearance and raised its efficiency to a very high order.

The difference it made is here in this quote:

Kayangulam Rajah had anticipated the fate of his army. He knew that his ill-trained Nayars were no match to the Travancore forces which had the advantage of European discipline and superior arms.

See these quotes also:

1. Harold S. Ferguson Esq.................then as Commandant of one of the battalions in the Travancore army (Nayar Brigade)

2. The armies of the chieftains consisted of Madampis (big landlords) and Nayars who were more a rabble of the cowardly proletariat than well-disciplined fighting men.

3. But Rodriguez not minding raised one wall and apprehending a fight the next day mounted two of his big guns. The sight of these guns frightened the Nayars and they retreated; the Moplahs too lost courage and looked on. The work of building the fort was vigorously pushed on even in the rainy season, and the whole fortress was completed by September 1519 A.D., and christened Fort Thomas.

4. [In this quote, you will see that De Lannoy, the Dutch man commanded the Travancore forces to attack the Dutch fort. On the Dutch side, it was the Nayars who fought.] Several battles were fought against the combined forces of the Kayangulam Rajah and the Dutch whose alliance gave the former fresh hopes. Much perseverance, stubbornness and heroism were displayed on both sides. Six thousand men of the Travancore army attacked the Dutch fort at Quilon which was gallantly defended by the Nayars commanded by one Achyuta Variyar, a Kariyakar of the Kayangulam Rajah.

5. The whole force was composed of Nayars, Sikhs, and Pathans under the supreme command of De Lannoy.

6. To effect economy in the military expenditure, Velu Tampi proposed a reduction of the allowances to the Nayar troops and in this he was cordially supported by the Resident. The proposal caused great discontent among the sepoys. They resolved on the subversion of the British power and influence in Travancore and the assassination both of the Dewan and the British Resident.

7. [This is with regard to Velu Tampi’s takeover attempt] Meanwhile the subsidiary force at Quilon was engaged in several actions with the Nayar troops. But as soon as they heard of the fall of the Aramboly lines, the Nayars losing all hopes of success dispersed in various directions.

8. After the death of Velu Tampi the rebels continued in arms here and there in parts of the Quilon district, but the arrival of the English forces soon brought them to their senses and order was quickly restored................... The Carnatic Brigade and some Nayar battalions were dismissed and the defence of the State was solely entrusted to the subsidiary force stationed at Quilon,

9. After the revolt of Velu Tampi in 1809, there was practically no army in Travancore. (Col) Munro organised two battalions of Nayar sepoys and one company of cavalry as “bodyguard and escort to Royalty”. ..............European officers were appointed to the command of this small force.

10. The Nayar Brigade. After the insurrection of 1809 the whole military force of Travancore was disbanded with the exception of about 700 men of the first Nayar battalion and a few mounted troops, who were retained for purposes of state and ceremony. In 1817 the Rani represented to the Resident Col. Munro her desire to increase the strength and efficiency of the army and to have it commanded by a European officer, as the existing force was of little use being undisciplined and un-provided with arms. On the strong recommendation of the Resident, the proposal was duly sanctioned by the Madras Government in 1818, and the Rani was given permission to increase her force by 1,200 men........................ Thus was organised the present Nayar Brigade, though the designation itself was given to it only in 1830 A.D.

11. The visit of His Excellency the Governor gave the Maharajah an opportunity to see the British forces in full parade. He was struck with their dress and drill and made arrangements for the improvement of his own forces after the British model. New accoutrements wore ordered and the commanding officer was asked to train the sepoys after the model of the British troops. The dress of the mounted troopers was improved and fresh horses were got down; and the appellation of the “Nayar Brigade” was first given to the Travancore forces. The Tovala stables were removed to Trivandrum and improved. On the advice of the Court of Directors, the European officers of the Nayar Brigade were relieved from attendance at the Hindu religious ceremonies.

12. A scheme for placing a portion of the Nayar Brigade on a more efficient footing was sanctioned in 1076 M.E (1900-1901) and came into operation in the next year. The two battalions that hitherto existed were amalgamated the sixteen companies were reduced to ten with a strength of 910 of all ranks. This reduction provided 500 men for the new battalion, which was styled the First Battalion and is intended for purely military duties following as far as possible the economy and discipline of the British Native Infantry.

This much is mentioned here, just because the Nair Brigade is often mentioned as a proof that the Nairs belong to the Kshatriya caste. However, the fact is that in contemporary times, in Malabar Thiyyas (a lower castes) were in the British-Indian army. At least one person I am aware was even a commissioned officer in the Royal Air Force. It does not mean that Thiyyas are Kshatriyas