After his marriage, Thompson took his place as one of the wealthiest inhabitants of the district in which he resided, and mixed in the best society which the colony afforded. It was not long before he made the acquaintance of his Excellency John Wentworth, the governor of the colony, who, anxious, no doubt, in the critical circumstances in which the American dependencies of Great Britain were then placed, to attach to the party which sided with the mother country as many influential colonists as he was able, lost no time in endeavoring to gain over so promising a man as Thompson. A vacancy having occurred in a regiment of the New Hampshire militia, Governor Wentworth gave the commission, which was that of major, to his new friend: an act of attention which, while it seems to have been gratifying to Thompson, did not fail to procure him much ill will from the officers already in the service, over whose heads he had been promoted. From this period Thompson began to be unpopular in his native province. He was represented as a friend of Great Britain, and an enemy to the interests of the colonies; and this charge was the more readily believed, on account of the marked kindness with which he continued to be treated by the governor, and the indifference which he exhibited to those political questions which were agitating all around him. The truth seems to be, that not only was Thompson, as a man in comfortable circumstances, and fond of the consideration and opportunities of enjoyment which they afforded him, averse to any disturbance, such as a war between the colonies and the mother country would cause, but that his constitution and temperament, his liking for calm intellectual pursuits, disqualified him from taking part in political agitation. Many men who have distinguished themselves in literature and science have, as a matter of principle, kept themselves aloof from the controversies and political dissensions of their time, alleging that, however important such questions might be, it was not in discussing them that their powers could be employed to most advantage. In the case of Thompson, however, who as yet had not begun to lay claim to the character of a man devoted to scientific pursuits, his countrymen thought, not altogether unreasonably, that they had grounds of complaint. What employment was he engaged in, that he ought to be exempted from the duty of a citizen - that of taking an interest in public affairs? So, probably, the most candid and considerate of the American patriots reasoned; and as for the great mass of the populace, they condemned him in the usual summary manner in which the public judges. Not a name was more detested in Massachusetts than that of Benjamin Thompson. He was denounced as a sycophant of the British a traitor to the interests of the colonies an enemy of liberty. To such a length did the public hatred of him proceed, that at length, in the month of November 1774, the mob of Concord had resolved to inflict on him the punishment which several other unpopular persons had already experienced - that of being tarred and feathered in the open streets. Receiving intelligence of the design of the mob before it could be carried into execution, Thompson had no alternative but to withdraw from Concord to some other part of the provinces where political excitement did not run so high. Accordingly, he quitted his wife and an infant daughter, who had been born in the previous year, and took refuge first in his native town of Woburn, from which he afterwards removed to Charleston. From Charleston, after a few months residence, he went to Boston, which was then garrisoned by a British army commanded by General Gage.
Thompson was well received by General Gage and the officers of the British army; and his intercourse with them, while it probably gave him a stronger bias towards the side of the mother country than he had yet exhibited, did not contribute to remove the bad opinion his countrymen had formed of his patriotism. Having returned in the spring of 1775, to his native town of Woburn, where he was joined by his wife and daughter, he again ran the risk of being tarred and feathered. The mob surrounded the house where he resided early one morning, armed with guns and sticks, and but for the interference of his old friend Loammi Baldwin, who arrived at the spot in time to use his influence with the crowd, serious consequences might have ensued.