During the Crimean War, when great pressure existed upon the hospitals at Scutari, Dr. Parkes was selected by Government to proceed to the seat of war to establish an additional large hospital. He fixed upon Rankioi on the Dardanelles, and his choice proved excellent. He worked most zealously to make everything as perfect as possible, and he accomplished much in spite of the red-tape which was so disastrously prominent in the war administration of that time. He did not in any way spare himself, though his constitution had shown serious signs of weakness in London, when he had had severe attacks of pneumonia and phlebitis. His report on the work of his hospital at the conclusion of the war was a most valuable one, and he gained the high esteem of Mr. Sidney Herbert, afterwards Lord Herbert of Lea. One result of the Royal Commission of Investigation into the administration of the war was the foundation of the Army Medical School, and Mr. Herbert never showed better judgment than in selecting Dr. Parkes to be Professor of Military Hygiene in connection with it. Consequently he gave up in 1860 his post at University College; he was appointed Emeritus Professor, and a marble bust of him was placed in the College museum. Parkes found that in order adequately to teach the subjects involved in preserving and promoting the health of the army, he must not only study the special features of army life and the peculiar liabilities attaching thereto, but also the general science of hygiene, then almost new. He organised at the cost of immense labour a detailed system of instruction, based on the principle of making the student apply practically what he taught. All the special questions which came up relating to air, water, food, temperature, clothing, house construction, drainage, &c., were as far as possible illustrated in the laboratory, and individual instruction was most carefully given. In 1864 was published the first edition of Parkes’s “Manual of Practical Hygiene,” a masterly book, accurate, learned, clear, full, and of the highest interest to the thoughtful mind. The introduction to this work opens with a clear definition of the subject. “Hygiene is the art of preserving health; that is, of obtaining the most perfect action of body and mind during as long a period as is consistent with the laws of life. In other words, it aims at rendering growth more perfect, decay less rapid, life more vigorous, death more remote.”