Some people who wrote war poems were not soldiers, but people at home, such as Rudyard Kipling (the author of The Jungle Book), Vera Brittain, Thomas Hardy and Charlotte Mew.
Themes
Some of the most common themes of war poetry are as follows:
Death
Life
Beauty
Religion
Nature
England/Englishness
Brotherhood and friendship
Emotion
Innocence
Here is an example of a short poem to get you thinking:
What is the secret-the secret
That lies at the heart of it all-
The surge of the stars, the cry of the wind,
And the beat of the sea,
And the surge and the cry, and the beat of the soul in me?
~Leslie Coulson~