http://globalresearch.ca/articles/CHU407A.html
Full text of the memo in question:
I do not understand this squeamishness about the use of gas. We have definitely adopted the position at the Peace Conference of arguing in favour of the retention of gas as a permanent method of warfare. It is sheer affectation to lacerate a man with the poisonous fragment of a bursting shell and to boggle at making his eyes water by means of lachrymatory gas.
I am strongly in favour of using poisoned gas against uncivilised tribes. The moral effect should be so good that the loss of life should be reduced to a minimum. It is not necessary to use only the most deadly gasses: gasses can be used which cause great inconvenience and would spread a lively terror and yet would leave no serious permanent effects on most of those affected.
I have two images of what Churchill wanted to do with chemical weapons here, based on his personal background and what he's saying.
1) Tear gas. If that's what he's thinking of, he's probably loving the idea of being able to scatter a tribal force from the air with gas, without killing
many of them and before any large deployment of ground troops has to be risked: war 'on the cheap,' with the same sort of push-button aspect that makes today's leaders enamored of drone strikes. He was pretty much indifferent to reports that such gases might blind or kill more vulnerable people. Coming out of World War One, the Boer War, and colonial wars in the Sudan and Afghanistan, this does not surprise me.
2) More lethal chemical weapons (chlorine and up); in this case he's
predicting that tribal forces (which he'd faced in battle in the 1890s) would scatter very quickly, after only brief exposure. Hell, I would too. Based on WWI experience, I suspect he would (correctly) expect that if people immediately fled the area of exposure, most of them would be only moderately effected- no serious permanent injury. The main thing that makes WWI-era chemical weapons a killer is if you try to stand and fight in an area saturated with them, or if they sink down into trenches and bunkers where you're sheltering to avoid more normal weapons like bullets and artillery.
Does this make him a murderous racist imperialist? Yes.
Still, the context is relevant; Churchill's standard of comparison for what happens when native forces try to oppose the British army was the Battle of Omdurman, and compared to the purely conventional slaughter at Omdurman, gas attacks look a bit less intense by comparison. Churchill took for granted that one way or another, any armed opposition to British dominance would get slaughtered; this was him proposing to do it with World War I weapons instead of 19th century weapons.
Does this make him a murderous racist imperialist?
Still yes.
For other interesting Churchill reading, I suggest his speech to Parliament in the wake of the Amritsar massacre, here:
http://lachlan.bluehaze.com.au/churchill/am-text.htm
[You will have to scroll down a bit; the page contains the tail end of a speech by someone else, who was defending the actions of General Dyer]