The role played by armament manufacturers in war has been missing from this debate .... sorry if I've missed any reference. A book, The Merchants of Death by Engelbrecht and Hanighen, 1934, deals extensively with this subject from the Middle Ages to the present (1934), covering events leading up to the 1914 war and after.
While agreeing that they (armament manufacturers) are not the sole cause of war, this quote by the biographer of Sir William Henry White who was a prolific British warship designer and Chief Constructor at the Admiralty is included:

Great armament firms have no national or political prejudices; they are concerned not with the ulterior objects of war, but with the immediate means by which victory may be secured; and the value of such abstract ideas as justice and Liberty they leave to the discussion of idle and metaphysical minds, or employ the terms as convenient euphemisms by which the real objects of statesmen may be cloaked and the energies of a people directed.

By the way, I read this book in gaol while servicing time as a consciensous objector.