When Between Decks was first exhibited in 1828, it shocked London audiences by confronting them with the grim realities of the transatlantic slave trade—a subject rarely treated so directly by an artist of J.M.W. Turner's stature. Inspired by the graphic testimony of abolitionist Thomas Clarkson, Turner chose not to romanticize or obscure, but to force viewers to witness the cramped, suffocating conditions endured by enslaved Africans during the Middle Passage.

The painting’s public debut coincided with a surge in British abolitionist sentiment, just five years before Parliament would outlaw slavery in its colonies. Turner captures a moment below the deck of a slave ship, where human bodies are packed tightly in the dim, oppressive hold. Shafts of sickly light pierce the gloom, illuminating faces marked by exhaustion and despair, while chains and fetters glint against bare skin. The composition compresses space, intensifying the claustrophobia and the sense of shared suffering; the viewer is not allowed to look away.

Unlike earlier depictions of slavery, such as those by John Singleton Copley, Turner’s focus is not on the spectacle above deck or the drama of rebellion, but on the silent endurance and humanity of the captives themselves. The precise medium of Between Decks remains uncertain, though it is likely a combination of watercolor and gouache on paper, reflecting Turner's experimental approach during the late 1820s. The painting was not a commissioned work, but rather a personal response to the abolitionist cause, and it remained in the artist’s studio until his death. After passing through the hands of private collectors, it eventually found a permanent home in a public collection, where it is now recognized as a rare and unflinching document of its era.

In Turner’s career, Between Decks stands apart for its social engagement and its refusal to offer consolation, marking a turning point toward the direct moral commentary seen in later works like The Slave Ship.