In 1831 he took up the Polish cause, and founded an association in London, which for many years was the main support of the unfortunate exiles who sought refuge in Britain. The public sympathy was at that time largely excited in their favour, not only by the gallant struggle which they had made for regaining their ancient independence, but from the subsequent severities perpetrated by the Russian government. Campbell, from his earliest years, had denounced the unprincipled partition of Poland; he watched the progress of the revolution with an anxiety almost amounting to fanaticism; and when the outbreak was at last put down by the strong hand of power, his passion exceeded all bounds. Day and night his thoughts were of Poland only: in his correspondence he hardly touched upon any other theme; and, carried away by his zeal to serve the exiles, he neglected his usual avocations. The mind of Campbell was naturally of an impulsive cast: but the fits were rather violent than enduring. This psychological tendency was, perhaps, his most serious misfortune, since it invariably prevented him from maturing the most important projects he conceived. Unless the scheme was such as could be executed with rapidity, he was apt to halt in the progress. He next became engaged in a new magazine speculation--_The Metropolitan_--which, instead of turning out, as he anticipated, a mine of wealth, very nearly involved him in serious pecuniary responsibility. After this, his public career gradually became less marked. The last poem which he published, _The Pilgrim of Glencoe_, exhibited few symptoms of the fire and energy conspicuous in his early efforts. "This work," says Dr Beattie, "in one or two instances was very favourably reviewed--in others, the tone of criticism was cold and austere; but neither praise nor censure could induce the public to judge for themselves; and silence, more fatal in such cases than censure, took the poem for a time under her wing. The poet himself expressed little surprise at the apathy with which his new volume had been received; but whatever indifference he felt for the influence it might have upon his reputation, he could not feel indifferent to the more immediate effect which a tardy or greatly diminished sale must have upon his prospects as a householder. 'A new poem from the pen of Campbell,' he was told, 'was as good as a bill at sight;' but, from some error in the drawing, as it turned out, it was not negotiable; and the expenses into which he had been led, by trusting too much to popular favour, were now to be defrayed from other sources." It ought, however, to be remarked, that he had now arrived at his great climacteric. He was sixty-four years of age, and his constitution, never very robust, began to exhibit symptoms of decay. Dr Beattie, who had long watched him with affectionate solicitude, in the double character of physician and friend, thus notes his observation of the change.