Having seen the discussion engendered by Iain on the Guards at Hougoumont, I was struck particularly by the claim that there was a southerly wind causing the fire to spread at Hougoumont. This surmise made on the back of an off hand comment by Wellington is wrong. The wind throughout the battle was westerly turning to north westerly later in the day. I remembered an excellent article on this which is to be found at https://rmets.onlinelibrary.wiley.com wea.246.04.pdf
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I agree that the exact weather at any location is up for debate, but wind directions are pretty certain.