World War I occurred between July of 1914 and November of 1918. At the time, it was the most deadly war in recorded history. Tens of millions of people were killed, and tens of millions more suffered injuries. Though it is hard to capture the horror of this war using the written word, there were many attempts.
Often, the most successful works of literature from the period came from those who actually served in the war. For instance, two of the most celebrated poets of the era were Wilfred Owen and Siegfried Sassoon, both of whom served in the military and wrote about their experience. Their poetry explored the psychology of the men who served and often questioned the value of that service.
The most famous novel written during World War I was All Quiet on the Western Front by Erich Maria Remarque, a text that explores the war from the German point of view. However, many famous novels were written after the war's conclusion, including Ernest Hemingway's A Farewell to Arms, Ford Madox Ford's Parade's End tetralogy, and Willa Cather's Pulitzer Prize–winning novel, One of Ours.
Furthermore, there is still literature being written in the contemporary moment about World War I, such as Pat Barker's Regeneration Trilogy. As such, it is difficult to say precisely what literature covers World War I. Even novels that do not engage directly with the subject often have the specter of the war in the background (such as Virginia Woolf's Mrs. Dalloway). Really, the influence of World War I is impossible to trace. It was a catastrophic event that really has no parallel in the modern day, and its influence continues to this day, albeit in an indirect manner.