Director Ken Loach is often called a “political filmmaker,” but in his 2006 Palme d’Or winner The Wind That Shakes the Barley — screening at Plaza Cinemas in Oxnard on Aug. 20 — he does not allow ideology to eclipse humanity, even though it is ideology that ultimately destroys the humanity of the characters. Set in Ireland during the War of Independence, the film is not merely a historical argument. Although it has reignited debate in Europe over the nature of the uprising, here in America, what we can glean from this powerful drama is a currently relevant, more universal theme, repeated numerous times in cinema, but not often with the riveting, realistic touch Loach brings to the screen: Is a cause thicker than blood?

Cillian Murphy and Padraic Delaney, as brothers united by revolution before being torn apart by it, are the heart of the story, both turning in gritty, tightly wound performances. Murphy is especially effective as Damien O’Donovan, a med school graduate bound for a London hospital until his friend is murdered by the Black and Tans, the paramilitary outfit founded to quash Irish rebellion against the British government in the early 1920s, for refusing to give them his name in English. He joins Delaney’s Teddy in the Irish Republican Army, and in each successive scene you can practically see the radical fervor rising in Murphy’s piercing blue eyes. Political discussions buffer the frequent outbursts of brutality, but despite the talky nature of the film, it is a role most powerful in its internalization. In the scene where Damien decides to kill a young boy he has known his entire life for betraying the group, it is not the actual shooting that unsettles as much as the moment directly afterward, when Damien drops the gun, turns and marches off silently through the strikingly green country field. He knows he has crossed a line: the point where an ideal becomes greater than friendship — even family.

Eventually, Damien’s idealism overwhelms him completely. In 1921, after a series of deadly ambushes by guerilla forces against the occupying officers, the Brits offer a peace treaty, granting Ireland greater control over its economy but still forcing its citizens to pledge allegiance to the Queen. Damien balks at the proposal. “This is what we fought for?” he asks incredulously. Teddy, however, thinks it is — as much as they could have expected, at least. And thus the brothers, and the rest of the country, splinter into two camps: those supporting the establishment of the Irish Free State, and those choosing to reject the offer and continue fighting for complete autonomy. The violence continues, only now it’s countryman versus countryman, and in the case of the O’Donovans, literally brother against brother.

In his portrayal of the British, Loach, an Englishman, goes the “inhuman monster” route; with the exception of one scrawny, guilt-ridden soldier who helps members of the IRA escape execution, the Black and Tans are painted with the same coat of callousness, beating elderly civilians for no reason and torturing insurgents by ripping their fingernails out. But he is less direct in his judgment of the civil war. Both sides are guilty of committing atrocities in the name of opposing beliefs. In the final tragedy, predictable yet still heartbreaking in its swiftness, Loach leaves us to question not the specifics of the period he is dramatizing but the value of martyrdom, and whether freedom is always worth the price of admission.