In April 1915 John was in the place near Ypres in Belgium in a area called Flanders, Unfortunately it was some of the worst fighting in World War I.
A day before he wrote his poem In Flanders Fields his best friend got killed. He was buried in the ground with a wooden cross and soon after poppies started to grow.
He was surrounded by the dead and dying and thousands of people being injured.
'In Flanders fields the poppies blow
Between the crosses, row on row,
That mark our place; and in the sky
The larks, still bravely singing, fly
Scarce heard amid the guns below.
We are the Dead. Short days ago
We lived, felt dawn, saw sunset glow,
Loved, and were loved, and now we lie
In Flanders fields.
Take up our quarrel with the foe:
To you from failing hands we throw
The torch, be yours to hold it high.
If ye break faith with us who die
We shall not sleep, though poppies grow
In Flanders fields'