The "Merchants of Death"-Ever Proven?

After WWI, there was great revulsion in Europe and the USA, over the horrendous loss of life and economic loss caused by the war. Many people claimed that the war was started (and continued) as a means for enriching the so-called “Merchants of Death”-these were firms like Vickers-Armstrong, Krupp, Schneider, Browning, that manufactured weapons. Muckrakers like Upton Sinclair wrote books (like “World’s End”) which linked the machinations of the armaments manufacturers, to the failed diplomacy that resulted in the war.
What I have never seen: a dispassionate analysis of the role of such firms. Specifically, what is the SD on:

  1. did these firms earn inordinate profits on their goods (as opposed to other manufacturers of the time)
  2. did these firms support politicians who clamored for war?
  3. did these firms collude with eachother, in an effort to increase business?
    My belief is that these firms played a minor role in the tragedy. I also think that war provides some short-term stimulus to economies-but long term, wars cause impoverishment and mis allocation of resources.
    Is there a good book that nalyzes this fairly and objectively?

The Nye Committee held lengthy hearings into this subject and turned up a good deal of innuendo, but little actual evidence.

Merchants of Death, by H.C. Engelbrecht and F.C. Hanighen, was a popular book on the subject in the '30s.
The Private Manufacture of Armaments, Vol.1, by Philip Noel-Baker is another I’ve got here somewhere (Vol.2 was never printed and apparently the manuscript remains with the League of Nations archives in Geneva. The author deferred his main conclusions for this volume)

A popular theme of the campaigners at the time was that if only the manufacture of arms was a monopoly of governments then all would be well. We can see how well that turned out.

There is some evidence of a price-fixing ring - the Warshipbuilder’s Committee - amongst the British shipyards in the '20s and '30s to share out scarce orders equably , which the Admiralty knew about and, to some extent connived at as a hidden subsidy to keep the yards in existence for the next war.

D.K. Brown, in From Nelson To Vanguard, comments that until about 1960, cost was not something naval architects worried much about. Studies were produced, the costing department put a figure on them, and Board of Admiralty decided what they could afford. Some quite trivial changes were vetoed as too expensive and often decisions were made without any real idea of the sums involved.
The costing group consisted of draughtsmen who used available data to produce simple rules of thumb, almost always a cost/ton figure for different weight groups, and extrapolated to show what the tender price for the next class of vessels should be. The figures were not particularly confidential, and it is quite likely that the shipyards were aware of them, and aware what would be expected and acceptable.