third was that tactics could be made into doctrine, but for Britain neither
operations nor strategy could.
Doctrine at the strategic level implied that the theatre of war—or of opera-
tions—could be anticipated in advance. Henderson, therefore, rejected doctrine,
and the Jominian legacy, as inappropriate for the British army. ‘War is assuredly
no mechanical art’, he wrote. ‘Broadly speaking, it is a war between the brains and
grit of the two commanders, in which each strives to outwit and outlast the other;
a conflict in which accident plays so prominent a part that mistakes, in one form
or another, are absolutely unavoidable’. 28 Instead of doctrine, Henderson looked
to principles, and even here he was at pains to stress that some principles
conflicted with each other, and that, therefore, ‘strategical principles are neither
to be rigidly applied nor over-scrupulously respected. They are to be obeyed
rather in the spirit than in the letter; and the strategist, to be successful, must
know exactly how far he can go in disregarding them or in modifying them’. 29
Henderson was a profoundly influential figure in the British army before
1914, the posthumous edition of his writings would be reprinted after the First
World War, and his principal historical study,Stonewall Jackson and the American
Civil War, would be studied at the Staff College long after that. Sir William
Robertson, who was at the Staff College in 1897–8, alongside Douglas Haig and
many others who would achieve fame in the First World War, wrote in his
memoirs that, ‘Of the different causes which are alleged to have given us the
victory over Germany, not one should be assigned a more prominent place than
the influence and teaching of Henderson at the Staff College’. 30
Robertson’s tribute is significant in view of his subsequent reputation. Hen-
derson expected the British army to be used in conformity with the expectations
created by its imperial commitments and by British sea power; Robertson, who
was Chief of the Imperial General Staff between late 1915 and early 1918, would
become—in the eyes of Liddell Hart and others who fell under his sway—the
arch-Continentalist, the man who used the creation of a British general staff to
subvert British generalship and to convert the British army into a mass army on
European lines. In 1902, the British army was uncertain of its role in national
policy, and the case for doctrine was accordingly easy to dismiss. In 1914–18, its
role would be clear enough: the issue, as it adapted, and as its colonial roles
became subordinated to Continental priorities, was whether it now needed
doctrine the better to wage European war. The debate was also a product of
increasing army size. The bigger the army and the more it depended on short-
term citizen soldiers, the greater the case for a doctrine that was committed to
paper rather than thinking that was informally transmitted. Moreover, size
created a wider gap between tactics and strategy: a command level emerged
that inserted itself between the tactical competence of the battalion and the
strategic role of the army. The corps practised the ‘tactics of the three arms
combined’, to use Henderson’s phrase, but it did more than that: it had to
accommodate not just field but also heavy artillery, not just cavalry but also
aircraft and, in due course, tanks. If operational art had an institutional home,
it would be the corps, a self-contained formation capable of independent
104 The Evolution of Operational Art