Here's a little more on the poem quoted in my last post, courtesy of Wikipedia.
Though various legends have developed as to the inspiration for the poem, the most commonly held belief is that McCrae wrote "In Flanders Fields" on May 3, 1915, the day after presiding over the funeral and burial of his friend Lieutenant Alexis Helmer, who had been killed during the Second Battle of Ypres. The poem was written as he sat upon the back of a medical field ambulance near an advance dressing post at Essex Farm, just north of Ypres. The poppy, which was a central feature of the poem, grew in great numbers in the spoiled earth of the battlefields and cemeteries of Flanders.
In 1855, British historian Lord Macaulay, writing about the site of the Battle of Landen (in modern Belgium, 100 miles from Ypres) in 1693, wrote "The next summer the soil, fertilised by twenty thousand corpses, broke forth into millions of poppies. The traveller who, on the road from Saint Tron to Tirlemont, saw that vast sheet of rich scarlet spreading from Landen to Neerwinden, could hardly help fancying that the figurative prediction of the Hebrew prophet was literally accomplished, that the earth was disclosing her blood, and refusing to cover the slain."
The Canadian government has placed a memorial to John McCrae that features "In Flanders Fields" at the site of the dressing station which sits beside the Commonwealth War Graves Commission's Essex Farm Cemetery. The Belgian government has named this site the "John McCrae Memorial Site".