Poetry written in the English language has a long and fascinating history. Like other creative arts, poetry began in service to communities. Its function was to aid the memory and enshrine in its rhythmic diction the history of the tribe, a way in which people could communicate not only stories but also ideas and emotions in an imaginative and expressive way providing a commentary - often critical - on what people, communities and nations do, expressing the horrors and irreversible changes created by modern warfare. During the 20th century many poets reacted to problems in the world with highly emotionally charged poems. The horror of war and the spiritual degradation it inflicts is evident in the work of the World War I poets. The present study aims at making a thematic study on the poetry written by major soldier poets during (1914-18). The themes of the poems are analyzed. Each theme was approached in two different ways. First epical, through the testimonies of soldiers and facts from historians to support better understanding of the poems , then poetical, when the war poets speak expressing their war experiences. The result was twenty-one themes classified under four groups (A, B, C & D). Keywords: rhythmic diction, horror of war, spiritual degradation, soldier poets, war experiences etc.