We may be into November but Josie Lawrence's Mother Courage is undoubtedly one of the performances of the year. Audience members familiar with her from TV comedy appearances will likely be shocked at the ferocity of her take on ‘Canteen Anna', the pragmatic, amoral merchant driving her cart through the centre of the Thirty Years War, making a buck wherever and however she can, ultimately losing her three children, her possessions and, quite possibly, her mind. I doubt that anybody who sees this extraordinary performance will ever forget it.

Lawrence conveys the "long burning rage" referred to in the text but also hints at an underlying kindness and compassion that hasn't quite been extinguished by the horrors of war. She may be tough as the old boots she's wearing but she also suggests more than any other Mother Courage I've seen that her love for her children is her prime motivating force. The moment where she lets out a long, silent scream after pretending not to recognise the corpse of one of her sons, or the scene where she reassures her tragic mute daughter Kattrin (Phoebe Vigor, devastating) that she won't leave her for a more comfortable life running an Inn, are painful to watch, and deeply moving. She is also mordantly funny, earthy and even sexy. This is the first version I've seen where the Chaplain's botched attempt to make a move on her may be motivated by desire as much as simple expediency. This is magnificent acting: unsentimental, emotionally raw, utterly truthful and entirely without vanity.

Hannah Chissick's engrossing staging has the actors address the audience directly at times, and uses the same Tony Kushner translation as the 2009 National production with Fiona Shaw, but in a smaller space it feels more urgent, less overblown, and allows us to focus on the lyricism and muscularity of the language. There is a savage beauty to this version that may slightly go against the Brechtian concept of alienation but it sure makes this sometimes harrowing piece a lot easier to sit through. The jagged, haunting score by Duke Special has an emotional punch that takes one by surprise, even if it too is somewhat at odds with what Brecht probably would have wanted.

The Thirty Years War was in the 1600s but Chissick and her designer Barney George have transformed Southwark Playhouse's larger space into a very modern war zone. When we enter there are sounds of far off explosions while a child plays centrestage with plastic toy soldiers, mimicking the sounds of destruction in an unsettling foreshadowing of what we will see over the next three hours, and the cast are dressed like the refugees that appear daily on our TV screens.

Welcome comic relief is provided by Laura Checkley, a brassy, blowsy knockout as prostitute Yvette, while Ben Fox and David Shelley are entirely convincing as the two men who fall under Mother Courage's spell. There is terrific work too from Julian Moore-Cooke and Jake Phillips Head as her doomed sons.

Ultimately though it is Lawrence's show and she is sensational. I will long remember the final image of her, almost broken and on the edge of despair, a victim of both her own avarice and the machinations of war, pulling her cart solo on to the next battlefield, and reaching out for help to an actual audience member. It is a heartstoppingly powerful moment in a performance full of them. Brecht's play isn't an easy one to love but its anti-war message is timeless and when it is presented with as much intelligence and theatrical flair as it is here it makes for essential viewing. Go.

Mother Courage and Her Children runs at Southwark Playhouse until 9 December.