<P> McCrae fought in the Second Battle of Ypres in the Flanders region of Belgium, where the German army launched one of the first chemical attacks in the history of war . They attacked French positions north of the Canadians with chlorine gas on April 22, 1915 but were unable to break through the Canadian line, which held for over two weeks . In a letter written to his mother, McCrae described the battle as a "nightmare", </P> <P> For seventeen days and seventeen nights none of us have had our clothes off, nor our boots even, except occasionally . In all that time while I was awake, gunfire and rifle fire never ceased for sixty seconds...And behind it all was the constant background of the sights of the dead, the wounded, the maimed, and a terrible anxiety lest the line should give way . </P> <P> Alexis Helmer, a close friend, was killed during the battle on May 2 . McCrae performed the burial service himself, at which time he noted how poppies quickly grew around the graves of those who died at Ypres . The next day, he composed the poem while sitting in the back of an ambulance at an Advanced Dressing Station outside Ypres . This location is today known as the John McCrae Memorial Site . </P> <P> The first chapter of In Flanders Fields and Other Poems, a 1919 collection of McCrae's works, gives the text of the poem as follows: </P>

Where was the poem in flanders fields written