In the opening stanza of the poem, McCrae uses symbolism when he describes "the crosses, row on row." The "crosses" he refers to here are the crosses that are used to mark the graves of soldiers killed during war. The crosses symbolize not only the deaths of the soldiers but also the bravery and honor of their deaths.
In the same stanza, the speaker says that there are "larks" flying overhead, above the graves. Larks, and birds in general, are often used in literature to symbolize freedom. In the context of this poem, the larks symbolize the freedom that the soldiers fought for and also perhaps the freedom from strife that these soldiers have attained in death.
At the end of the first stanza there is an example of juxtaposition when McCrae describes the singing of the larks "in the sky" being drowned out by the firing of "the guns below." This juxtaposition, between the birds singing overhead and the guns firing below, reflects the link between freedom and violence. In World War I, soldiers believed that the violence of war was a necessary means by which to win freedom for their countries.
In the second stanza the speaker says that the soldiers who are now dead "loved and were loved." The repetition of the word "loved" emphasizes the point that these soldiers were people with families, whom they lost and who lost them.
In the third and final stanza there is another example of symbolism when the speaker says that the soldiers who have died in the war have passed "the torch" on to the next generation. The "torch" here symbolizes the hope that the dead soldiers fought for and which the next generation must keep alive in order to honor the memories of those dead soldiers.