This book was first published in 1936. In it Steinbeck addresses such social issues as the precarity of the migrant worker (especially during the Great Depression years), the exploitation of the poor in the agricultural sector, and the need for a collective identity in a mutating economic community.
Steinbeck (onces again!) draws partial inspiration from an earlier, classical work:
In Dubious Battle takes its title from Milton's Paradise Lost, Book I (1658), in which Satan vows to engage the forces of heaven In Dubious Battle even if it means eternal vanquishment. That reference sets a tone for Steinbeck's novel, and suggests a way to view the main characters: as Satan-like figures, not because they are inherently or necessarily evil, but because they are determined to persevere in their battle against capitalism even when odds for success are overwhelmingly against them.
This work, heralding his epic-scale saga The Grapes of Wrath (published two years later), contrasts sharply with Steinbeck's idyllic portrayals of collective unity and solidarity in Tortilla Flat, Cannery Row and Sweet Thursday.
Check out the following references concerning Steinbeck's disenchantment with both communism and American idealism as ideologies.