Every new invention makes the problem of co-operation--of interaction between the different armies and services--more difficult and more imperative.
* * * * * As to the artillery history of the war, the Field Marshal gives the most amazing figures.

When in 1916, at the suggestion of Mr.
Roosevelt, and by the wish of our Government, I went through some of our leading munition districts, with a view to reporting what was being done in them to England's friends in America, the great development which started from the Munitions Act of 1915 was still only in its earlier stages.

Everywhere the Government factories were rising with what seemed incredible rapidity, and the older works were doubling and trebling their output.

But the output was still far behind the need.

By the date of the Somme Battle, indeed--in the autumn, that is, of the same year--it had risen enormously.