The reason that more recent histories are kinder to the perpetrators if WWI is that those writing them are too young to have heard many first hand accounts of its horrors. They may have read war diaries, but largely not these either. Also, the point raised by Guest is pertinant, there is a conscious effort by modern politicians, and Gove is but one, to whitewash the past in order to strengthen their justification for repeating its mistakes. Eric Bogle summed it in the verse, disgracefully omitted by Joss Stone and the British Legion in their sanitised version of No Mans Land:

"And I can't help but wonder, now Willie Mcbride,
Do all those who lie here know why they died?
Did you really believe them when they told you 'The Cause? '
Did you really believe that this war would end wars?
Well the suffering, the sorrow, the glory, the shame
The killing, the dying, it was all done in vain,
For Willie McBride, it all happened again,
And again, and again, and again, and again."

Killing and Dying will always be done in vain whilst the outcomes are dictated by the egos of politicians. Modern Historians are just their useful idiots.