This post will show the readers one of the fifty-something lieutenants perceived as "too old for their rank":
The lieutenant, whom we mentioned in the preceding chapter, and who commanded this party, was now near sixty years of age. He had entered very young into the army, and had served in the capacity of an ensign at the battle of Tannieres; here he had received two wounds, and had so well distinguished himself, that he was by the Duke of Marlborough advanced to be a lieutenant, immediately after that battle.
In this commission he had continued ever since, viz., near forty years; during which time he had seen vast numbers preferred over his head, and had now the mortification to be commanded by boys, whose fathers were at nurse when he first entered into the service.
Nor was this ill success in his profession solely owing to his having no friends among the men in power. He had the misfortune to incur the displeasure of his colonel, who for many years continued in the command of this regiment. Nor did he owe the implacable ill-will which this man bore him to any neglect or deficiency as an officer, nor indeed to any fault in himself; but solely to the indiscretion of his wife, who was a very beautiful woman, and who, though she was remarkably fond of her husband, would not purchase his preferment at the expense of certain favours which the colonel required of her.
The poor lieutenant was more peculiarly unhappy in this, that while he felt the effects of the enmity of his colonel, he neither knew, nor suspected, that he really bore him any; for he could not suspect an ill-will for which he was not conscious of giving any cause; and his wife, fearing what her husband's nice regard to his honour might have occasioned, contented herself with preserving her virtue without enjoying the triumphs of her conquest.
This unfortunate officer (for so I think he may be called) had many good qualities besides his merit in his profession; for he was a religious, honest, good-natured man; and had behaved so well in his command, that he was highly esteemed and beloved not only by the soldiers of his own company, but by the whole regiment.
Henry Fielding, The History of Tom Jones a Foundling.