The flowers left thick at nightfall in the wood
This Eastertide call into mind the men,
Now far from home, who, with their sweethearts, should
Have gathered them and will do never again.
Flowers, while often linked with fertility, beauty and celebration, are also associated with death and funerals. Here, they are “left thick”, implying mulitiple deaths and consequent mourning by those left behind. 
 It is appropriate that the poem should be set at nightfall, the close of day and the close of life. A wood can be shady but can also be strange and frightening. 
 Wood is also a  homophone  for the conditional “would”, this being a poem about what might have been. 

In Memoriam Easter 1915