Starring: Cillian Murphy, Padraic Delaney, Liam Cunningham, Gerard Kearney, William Ruane. Not Rated.

The Wind That Shakes the Barley, recipient of the Palme D’Or at last year’s Cannes film festival, is the latest from English director Ken Loach, a committed leftist who has spent much of his 45-year career turning his political meditations into popular entertainment. Barley is no exception. Set in the early 1920s, it recalls a violent insurgency staged by the Irish Republican Army against a rogue British paramilitary unit known as the Black and Tans. And though it’s no secret where Loach’s sympathies lie – he has always sided with the weak against the powerful, and, more specifically, the working-class Irish against their onetime oppressors in Parliament – his impassioned yet even-handed history resonates forcefully.

His film, written by frequent collaborator Paul Laverty, examines the relationship between two brothers, Damien (Cillian Murphy, of 28 Days Later), a young doctor-in-training, and Teddy (Padraic Delaney), a soldier defined not only by his fiery temper but also his political pragmatism. Both are dedicated to the IRA, and despite Damien’s gentler disposition, both commit vicious acts in its name, including the murder of a boy who betrays their small band of revolutionaries to the British. Together, they suffer imprisonment and torture, and the experience only strengthens their resolve.

When Ireland is granted a measure of autonomy, but not full independence, by the Anglo-Irish Treaty of 1921, the IRA divides into two rival sects – those like Teddy, who see the so-called Free State as a significant step forward, and those like Damien, who consider it an insufficient concession and a betrayal of the cause. Thus begins a period of civil war. When, for the first time in their lives, the brothers find themselves on opposing sides, it seems inevitable that their rift will end in bloodshed.

Although Loach clearly favors the revolutionaries who cling steadfastly to the notion of an independent Ireland, his approach is honest and unflinching: The Black and Tans are sadistic bullies, but for all the atrocities committed in defense of English rule, the IRA’s tactics are often equally brutal. Indeed, The Wind That Shakes the Barley is rarely easy to watch, with its matter-of-fact depictions of extreme violence reflecting the harsh realities of a turbulent time. Yet with Damien and Teddy, whose underlying humanity is convincingly conveyed by Murphy and Delaney, he delivers a moving and often beautiful story that captures the essence of the conflict, with all its unintended consequences and personal tragedies.