Editing Battle of Passchendaele (section)

====Weather====
[[File:18pdrInMudZillebeke9August1917.jpg|thumb|left|{{centre|Royal Field Artillery gunners hauling an 18-pounder field gun out of the mud near Zillebeke, 9 August 1917}}]]
In ''Field Marshal Earl Haig'' (1929), Brigadier-General [[John Charteris]], the BEF Chief of Intelligence from 1915 to 1918, wrote that

{{blockquote|Careful investigation of records of more than eighty years showed that in Flanders the weather broke early each August with the regularity of the Indian monsoon: once the Autumn rains set in difficulties would be greatly enhanced....Unfortunately, there now set in the wettest August for thirty years.|Charteris{{sfn|Charteris|1929|pp=272–273}}}}

only the first part of which was quoted by Lloyd George (1934), Liddell Hart (1934) and Leon Wolff (1959); in a 1997 essay, John Hussey called the passage by Charteris "baffling".{{sfn|Hussey|1997|p=155}} The BEF had set up a Meteorological Section under [[Ernest Gold (meteorologist)|Ernest Gold]] in 1915, which by the end of 1917 had {{nowrap|16 officers}} and {{nowrap|82 men.}} The section predicted the warm weather and thunderstorms of 7 to 14 June; in a letter to the press of 17 January 1958, Gold wrote that the facts of the Flanders climate contradicted Charteris.{{sfn|Hussey|1997|p=153}} In 1989, Philip Griffiths examined August weather in Flanders for the thirty years before 1916 and found that,

{{blockquote|...there is no reason to suggest that the weather broke early in the month with any regularity.|Griffiths{{sfn|Hussey|1997|pp=147–148}}}}

From 1901 to 1916, records from a weather station at [[Cap Gris Nez]] showed that {{nowrap|65 per cent}} of August days were dry and that from 1913 to 1916, there were {{nowrap|26, 23, 23 and 21}} rainless days and monthly rainfall of {{cvt|17|,|28|,|22|and| 96|mm|in}};

{{blockquote|...during the summers preceding the Flanders campaign August days were more often dry than wet.|Griffiths{{sfn|Hussey|1997|p=148}}}}

There were {{cvt|127|mm}} of rain in August 1917 and {{cvt|84|mm}} of the total fell on {{nowrap|1, 8, 14, 26 and}} {{nowrap|27 August.}} The month was overcast and windless, which much reduced evaporation. Divided into two ten-day and an eleven-day period, there were {{cvt|53.6|,|32.4|and|41.3|mm}} of rain; in the {{nowrap|61 hours}} before {{nowrap|6:00&nbsp;p.m.}} on 31 July, {{cvt|12.5|mm}} fell. From {{nowrap|6:00&nbsp;p.m.}} on 31 July to {{nowrap|6:00&nbsp;p.m.}} on 4 August, there was another {{cvt|63|mm}} of rain. August 1917 had three dry days and {{nowrap|14 days}} with less than {{cvt|1|mm}} of rain. Three days were sunless and one had six minutes of sunshine; from 1 to 27 August there were {{nowrap|178.1 hours}} of sunshine, an average of {{nowrap|6.6 hours}} per day. Hussey wrote that the wet weather in August 1917 was exceptional and that Haig had been justified in expecting little rain and that it would be dried swiftly by sunshine and breezes.{{sfn|Hussey|1997|pp=149–151}}