"In Flanders Fields" is a lyric poem by John McCrae inspired by the death of his close friend during World War I. The poem is both a lament for the dead soldiers buried at Flanders and a celebration of the courage of the living to carry on with their lives.
On the surface, the poem serves merely to memorialize the young soldiers who died in the Flanders region of Belgium during World War I. On closer inspection, the poem also carries a "carpe diem" message -- the dead were enjoying sunsets and the company of others "short days ago," but now they are dead and buried. The poem reminds the reader that life can be cut tragically short, and urges him to enjoy it while he can.
The poem also implies that the living owe the dead soldiers a duty. The last stanza ("...the torch; be yours to hold it high") suggests that the living are now the metaphorical "torchbearers," and that the fight (against prejudice, intolerance, ignorance, or other future evils) is now theirs.
Lastly, the poem is about the courage of the living to go on with their lives after suffering the loss of loved ones at war. McCrae characterizes the living as "larks, still bravely singing" and flying above the graves of fallen soldiers, commending them for living without fear even during the chaos of war.