The Order of Isabella the Catholic was subsequently conferred on him, with promotion, for his gallantry before Madrid, but a wound received in the foot, which caused him much suffering and refused to heal, compelled him to ask for sick leave. As he was with difficulty wending his way homeward he was pursued by the enemy and abandoned by his guide. After hiding for three days he was captured and imprisoned with three other foreigners. Feigning an illness which afterwards became real, he was removed to a hospital. The English doctor in attendance knew only of the prisoner's feint and admired the natural way in which the shivering fits were counterfeited. In vain the patient, who was really ill, protested that he was so, until after a time the truth of his assertion became apparent, for typhus fever had declared itself and the doctor was, too late, convinced of it. For twenty-one days Henningsen's life was despaired of, during which time his friends interceded for him. His release was demanded by the British Government, but General Espartero sternly refused it, saying his life was forfeited, for he had both with his sword and pen proved himself a dangerous foe. At the reiterated request of Lord Palmerston, backed by the Duke of Wellington and others, Espartero, however, was compelled to yield, as the withdrawal of the foreign legion was threatened if he persisted in his refusal. Henningsen, on his return to England, published a couple of volumes of personal recollections, which still hold a place in literature. His story was told in a simple and direct style, which showed marked literary ability. But the world was then too full of doing, for an active mind to content itself with thinking or saying. Schamyl the Prophet had unfurled his sacred banner, lit the fires of revolution on the Caucasus, and thrown the gage of battle to the mighty Czar himself. His cause was just enough, his case was desperate enough, to enlist the sympathies of the young knight-errant, who soon found himself battling beside wild mountaineers in Caucasian snows, and completing the education begun on the vine-clad hills of Spain. That campaign over, he improved his leisure in writing two or three books on Russian life, which increased his literary reputation without inducing him to take up a life of letters. The restraints of civilisation were too irksome, and he fled to the wilds of Asia Minor, where the news of Hungary's revolt against Austrian and Russian despotism found him. He arrived on the scene of action too late to take part in anything but the sorrowful ending. Gorgey's treason, if such indeed it were, had turned the scale against the patriots. Henningsen submitted a plan of operations to Kossuth, who decided that it was now too late for offensive action. All that remained was to offer his sword to the forlorn hope. The offer was gladly accepted. He joined Bem in the last ditch at Komorn, aiding not a little in the stout defence of that place.