The BBC showed ""World War One from above" on Sunday. It's still available on-line but probably only in the U.K. (Note the consequent careful spelling of programme - with 2 "m"s and an "e") .
A French aviator filmed the Western front battlefields from a balloon, shortly after the war ended. That filming was linked to well researched background material, with a particularly good account of the Messines Ridge battle, which Harry took part in. (Chapter 4 of the book - June 1917 in the blog).
The programme suggested that the Messines mines were set off sequentially, working to the south - that the Germans in the southernmost trenches watched with increasing horror as a vision of Armageddon approached. All accounts I've read indicated that the mines were fired simultaneously at precisely 3 am. ( I don't see any significant military benefit in a sequential system - with only seconds between detonations.) Does anyone have any more information?
Update. I'm reading Nicholas Rankin's excellent book "Churchill's Wizards". In it he describes "a rolling sequence that lasted an appalling 28 seconds". I don't know if that was the intention or the result of imprecise timings. Access to the orders for the attack, at army level, may be able to answer that one.
I found the whole programme to be excellent. Particularly chilling were the views of the water filled shell holes across the Passchendaele battlefield. Not just a few, the whole battlefield completely covered with, what looked from the air like puddles, but which were actually small lakes that would easily drown a man laden with military equipment.
This week, the blog should pass another milestone with the three millionth pageload. There are still over a thousand visitors a day with a steady flow of positive and rewarding comments.
Posted by Pte Harry Lamin at 10:59 am