The military activities of Thomas remained confined in Haryana and he did not face any strong resistance from the local inhabitants unitedly in establishing his principality in this region. The reason is apparent that the people of Haryana were not united in a single body as the Sikhs were.

Born in a poor Irish family of Tipperary (Ireland) in 1756 A.D, George Thomas could not get proper education.’ He became a sailor and arrived in India in 1781-82. As God had stored much more for him, he left the existing position and joined Nizam Ali Khan’s army as a gunner. In 1787 he got a commission in the service of Begum Sumru, who appointed him  as a collector (District Magistrate) of Tappal. He took keen interest and doubled the revenue of it. He suppressed the law-breakers, but in an intrigue, he was arrested and confined in 1791. However, he was released by the efforts undertaken by Shah Nizam-ud-Din, an agent of Mahadji at the Imperial Court. He went to Anupshahar and remained there for some time. Thomas was an intrepid soldier and could not remain in isolation for a long time. In 1793, he entered in the service of Apa Khande Rao, the Maratha Governor of Southern Haryana, who directed him to raise a battalion of 1,000 cavalry. In 1794, Thomas collected the revenue forcibly from the peasants of Western Haryana. Tijara, Tapukra and Firozepur-Zirkha were assigned to him so that he could maintain more troops. Having taken possession of Tijara in March 1794, he plundered Bahadurgarh, Jhajjar, Pataudi and other surrounding villages and included all these places in his jagir and raised an income of one and a half lakhs rupees a year.

Although Thomas had established his authority over some parts of Haryana, yet a courageous Ganga Bishan, Ahir and a principal zamindar alongwith 14,000 men of his tribe, made a representation. He resolved to hand over his district to Gopal Rao Bhau. Apa could not bear this and directed Thomas to punish Ganga Bishan. On his arrival, the zamindar fled towards the mountains of Mewat. Thomas pursued and captured him. Later, he was sent to Apa. Still the people of Haryana did not lose heart and continued to make a tough resistance against bravado Thomas. The capture of Ben, in the year 1794, is an interesting story. “In the fort (says Mr. Thomas) exclusive of the garrison, were 300 Rajpoots and Jaats. These had been hired for the express purpose of defending the place and it was here I was in the most imminent danger of losing the whole of my party....the danger was every moment increasing, the town was on a fire in several parts, and our retreat nearly put off by the flames that surrounded us.” “In this situation,we had the additional mortification to perceive the merciless enemy seize on the wounded officer, and with savage barbarity, precipitate him into the fire.

Equally animated, as enraged by this spectacle, my troops now rushed forward to attack, with an ardour that was irresistible. Having gained entire possession of the fort, the soldiers with clamorous expression of revenge, insisted on the death of every one of the garrison that remained and I was not inclined to rescue; but it cost us dear; the enemy to a man made a brave resistance. This contest was continued so long as to afford time to those who had retreated to return. By this means, we were again engaged; and at one time almost overpowered; but receiving a reinforcement of our own party, the enemy, once more made a stand in the jungles, adjoining the town, when, after a second desperate conflict; they gave way on all sides and most of them were out to pieces.” Thus, the Haryanavies laid down the lives for the sake of their country.

The repeated success of Thomas in Haryana aroused jealousy of Begum Sumru. Levasso, an inveterate enemy of Thomas added fuel to fire. Begum’s army consisting of 4 battalions of infantry, 20 companies of artillery and 400 cavalry, moved from Sirdhana, her capital. She encamped about 34 miles South-East of Jhajjar.’ Mr Thomas’ regiment consisted of 2,000 men, 10 pieces of artillery, 500 irregular and 200 cavalry. As he had a good luck, a dissension aroused in the troops of Levasso, who was the Chief Commander, and had enmity with Legois, a German, who was a friend of Thomas. He dissuaded Begum not to attack upon Thomas. She paid little attention to his advice and Legois was replaced by a junior officer. On this, his troops revolted and the Begum was made prisoner. Levasso could not bear this and shot himself, and immediately fell from  his horse.

“The villians (says Thomas), who the preceding day had  styled themselves, his slaves, now committed every act of insult and indignity upon his corpse.” After three days it was thrown into a ditch. In this way, the ensuing danger was warded off. Being a free man, he moved  towards Narnaul and took possession of it. Here, Khande Rao bestowed an elephant, a pallanquin, shawls and other valuable articles to Thomas. In 1795, 5,000 Sikhs entered the Upper Doab and plundered the territory. Before the Sikhs, “the local militia made no stand against them. The Maratha garrisons in Saharanpur were scattered like chaff before the wind.” Apa Khanda Rao utilised the services of Mr. Thomas in ousting the Sikhs. The Sikhs wisely returned to Panjab. Lakhwa Dada put him on duty to guard the Yamuna-frontier of the Upper Doab with a contingent of 2,000 infantry and 200 cavalry and 16 pieces of artillery and assigned him the parganas of Panipat, Sonepat and Karnal in order to maintain his additional troops. One would be surprised to know that the Marathas had destroyed the Western Yamuna Canal. Consequently, it yielded only one lakh of rupees, which yielded revenue of rupees 14 lakh per year earlier.” Thomas remained busy during the entire year of 1796 in warding off the Sikhs.

The Sikhs  continued to plunder the Upper Doab and Thomas had to fight with them on both sides of the Yamuna.  On 25 June, 1797,Apa Khande Rao was drowned in the Yamuna and was succeeded by his nephew Vaman Rao. The Maratha administration was deteriorating. Thomas could not get the promised pay from the successor of Apa and found the income of his jagir unequal to meet the expenses of his troops. Thomas had no argent comptant for his army. He became bandolero and “began to support himself by filibustering  raids on the towns and villages of his neighbours, without any regard whatever for the elementary laws of property.’ In 1797 he made a raid from Jhajjar upon Urika, a town of Jaipur and collected 52,000 rupees from there. In early 1798 Lakhwa Dada  ordered Vaman Rao, to raid Jaipur for collecting the tribute due from the State. He was to be assisted by Thomas, who was promised to be paid rupees 50,000 a month. Thomas’ army consisted of three battalions of infantry, 300 Ruhela musketeers, 200 jawans of Haryana, 90 horsemen  and 14 pieces of artillery. They started from Karnal and entered the north side of Kachhwa kingdom. On the way they collected the revenue from the villagers. A battle was fought near Fatehpur in February 1798. The Maratha cavalry supporting Thomas fled away. Consequently, a large number of his men were put to the sword. “The moment was critical. Mr. Thomas, with the only gun that remained which he loaded upto the mussle, and about 150 of his followers waited the event with fortitude. After permitting the enemy to approach within forty-yards, he gave them three discharges of his guns accompanied by three volleys of musketry.” Thus the enemy was routed completely.

Thomas apprehended the flight of Marathas in the  battle and resolved to withdrew his earlier support. Now he wanted to establish his own independent principality in Haryana. In order to fulfil his dreams, he chose the ‘No Man’s Land’ west of Rewari—Delhi—Karnal districts and south of Patiala. He established his capital at Hansi. Haryana had not acknowledged any ruler for the last many years. It had been a battle field for contending powers. Sir Jadunath Sarkar writes, “The tract of land under the rule of George Thomas was oval in shape, with ill-defined and ever-shifting frontiers. It extended 32 to 48 miles in different directions. On the north lay the Ghagher river which separated it from the lands under Sikh occupation; on the west the country of the predatory Bhatti tribe, beyond which lay the deserts of Bikaner. The south was bounded by the Rewari district.” In most parts of this tract, water is scarce. Hence the inhabitants have constructed wells often 120 to 150 or even 200 feet deep. In the Hissar district there are 300 such wells.” He spent the whole month of May 1798 in repairing the dilapidated fort of Hansi. Being a militarist, he led expeditions and took possession of southern Haryana. But still, he had to face Bhattis, the Raja of Patiala and other Sikh chiefs who were ruling on north-west Haryana. At Hansi, he felt a great difficulty in procuring the inhabitants as it was a deserted city. But he treated the people of surrounding areas with mildness. Thus its population rose to 6,000 souls as he himself writes: “I selected between five and six thousand persons to whom I  allowed every lawful indulgence.” Here he established a mint and coined his own rupees (Sikka-isahib anno Hijri 1214). He made his coins current in his army and country.

He also employed a large number, of workmen and artificers.” “I now judged that nothing but force of arms could maintain my authority. I, therefore, increased their number cast in my own artillery, commenced making musquets, match-locks and gun powder and in short made the best preparations for carrying on an offensive and defensive war till at length having gained a capital and country bordering on the Sikhs’  territories...” Thomas had an insatiable desire to extend his territory. So, he marched out of Hansi and seized the fort of Gokulgarh — two miles from and belonging to Sindhia, a local Governor. Then he moved ahead and took possession of Bahadurgarh. He also attacked Bhag Singh, a raja of Jind, but he had to wheel back as he was supported by other Sikh chiefs, particularly by Bibi Sahib Kaur of Patiala. However, in February 1799 he had to come back.” Thomas did not lose heart and in January 1800 he marched towards Safidon and besieged it for two hours. In the struggle, Mr. Hopkins was wounded. Meanwhile, he received an invitation from Bibi Sahib Kaur, who was imprisoned by her brother, the raja of Patiala, which compelled the raja to surrender the districts of Budsikri, Jamalpur and Tohana from Patiala, Kapori from Kaithal of Budsikri, and Safidon from Jind, and also release his sister. He also plundered Sirsa, a fort belonging to Bhattis and collected immense booty. On the way, he also plundered Kaithal. Thomas, having established himself in Haryana, resolved to plant the British standard on the banks of Attock. In the  beginning of January 1801, Thomas again invaded Patiala.

At this time “the whole Khalsa force of that region came together, enveloped the invader, and cut him off from the base (end of March 1801).” Thomas had to retreat to his dominions. Since he had already faced the bellicose Sikhs, who prevented him to move ahead, it seemed, that he resolved to remain in Haryana, where he had not great opposition  from the local inhabitants at least.In April 1801, he again moved towards Jind. Bhag Siagh, the raja of Jind, got the support from  French General Perron, whom Daulat Rao Sindhia had made his supreme Commander in North-  India. He had collected a large force in order to annihilate him in Haryana. On the instigation, some of men deserted Thomas and joined Perron. So his, fall was “as meteoric as his rise.” In September 1801, Perron sent Major Louis Bourquien towards Georgegarh. Thomas rapidly marched from Hansi but he was intercepted by  Bourquein. A battle was fought on 1st October, 1801, but without result. However, Bourquein got the timely help from the Sikhs.