John Steinbeck's experiences as a war correspondent during World War II significantly shaped his literary voice. Encountering the realities of combat and the tumult of human suffering deepened his understanding of humanity and social issues. His war experiences influenced the themes in novels like "The Grapes of Wrath," emphasizing the struggles of the working class during the Great Depression. Steinbeck’s empathy for both the characters and the plight of ordinary individuals highlighted the impact of social injustices, forming a powerful narrative style rooted in realism and a commitment to advocacy.