Both of these poems concern war and the poet's response to it. In "I Sit and Sew," for example, the speaker finds her position as a woman, who has to do nothing else but "sit and sew" whilst she imagines all the men who are suffering and dying in war, intolerable, and stifling. Note how this is shown in the following quote:
My soul in pity flings
Appealing cries, yearning only to go
There in that holocaust of hell, those fields of woe—
But—I must sit and sew.
Note how the description of the war fields emphasises the suffering and pain that the soldiers there endure: it is a "holocaust of hell" and the fields are "fields of woe." The way in which the speaker finds her situation so hard to handle is shown through the verb "must" which indicates her lack of choice and her desire to go and do something to help rather than do something so ineffectual and pointless.
In "April is on the Way," a slightly different tone is taken. Whereas in "I Sit and Sew," the overall feeling is one of anger and frustration, in this poem, there is a hopeful tone, as April, with its accompanying rebirth of nature, helps the speaker to trust in God's power of resurrection for the human:
April is on the way!
The infinite miracle of unfolding life in the brown February fields.
(Dear God, the hounds are baying!)
Murder and wasted love, lust and weariness, deceit and vainglory—what are they
but the spent breath of the runner?
This quote compares the various vices and sins of man to the "infinite miracle of unfolding life." In God's bigger picture of what he does in the world and his work in nature, the speaker is able to find hope in the belief that God's forces and powers of resurrection are so much greater and bigger than any of man's actions, including war.