Now that the 100th anniversary of the outbreak of the First World War is fast approaching, a major exhibition of Stanley Spencer’s response to the conflict has opened in London and will travel to Pallant House, Chichester.

Having worked as a hospital orderly near Bristol and then served with the Royal Army Medical Corps in Macedonia, Spencer became obsessed by the idea of creating a masterpiece based on his experiences.

His ambition was realised inside the Sandham Memorial Chapel at Burghclere, Berkshire, completed in 1932 after six arduous years of work. Commissioned by John Louis and Mary Behrend, the chapel is dedicated to Mrs Behrend’s brother Lieutenant Harry Sandham, who died of an illness contracted during the war. Now the National Trust is lending many of Spencer’s paintings to the exhibition at Somerset House, while important restoration work is carried out at the chapel. Spencer’s vision was based on his love of Giotto, in particular the paintings for the Arena Chapel in Padua. But the Sandham paintings are rooted in his own memories of the war, from teatime in a hospital near Bristol, to soldiers map reading in Macedonia. The most monumental painting, a powerful resurrection scene above the altar at Sandham, cannot be moved. Instead it is being projected in the Terrace Rooms at Somerset House for the show.

Since Spencer completed his chapel paintings, nothing quite as ambitious or elaborate has been made in Britain by an artist focusing on war. But it would be a mistake to imagine that contemporary practitioners have failed to produce memorable war art. ‘Catalyst’, at the Imperial War Museum North in Manchester, shows work executed by more than 40 artists since the first Gulf War over 20 years ago.

This is an impressive show, drawn entirely from the IWM’s collection. Before we enter, our attention is arrested by an enormous, mangled, bronze-coloured object that Jeremy Deller retrieved from Iraq. It is a car destroyed by a bomb in a Baghdad marketplace where book-lovers liked to congregate. The explosion occurred on 5 March, 2007, killing 36 people and injuring over 100 more. It is essentially a found object that Deller has not altered, and its relocation to an exhibition space testifies to the horrific brutality of the Iraq conflict.

Deller’s exhibit prepares us for a different yet equally disturbing work inside – an image of Tony Blair grinning with boyish delight as he takes a photograph of himself in front of an enormous explosion. The photomontage was made by Peter Kennard and Cat Picton-Phillipps, known as kennardphillipps. Like many people in Britain, they were angered by Blair’s insistence on defying public opinion and going to war in Iraq.

Commissioned by IWM in 2002 to respond to 9/11 and the Afghan War, artist duo Langlands & Bell were fascinated to hear about Osama bin Laden’s abandoned home in Daruntah, eastern Afghanistan. Having gone out to photograph the house, they made an interactive video-game animation that invites us to search the building and its surroundings. Our efforts to find the terrorist leader prove futile, highlighting the frustration experienced by those who struggled for several years to capture him. As we race through room after empty room, we feel giddy and almost nauseated, which makes us think about war in a suitably unnerving way.

As does Ori Gersht, whose twin-screen film, Will You Dance For Me (2011, top), is based on the memories of Yehudit Arnon. Imprisoned at Auschwitz during the Second World War, she was commanded to dance at an SS officers’ Christmas party. After refusing, she was ordered to stand barefoot outside in the snow for hours.

At first we only hear Arnon’s voice describing her ordeal. But then her 85-year-old face looms out of the darkness, looking haggard and determined. She recedes into the distance on er rocking chair, then both screens are filled with a snowy landscape. Gersht makes eloquent use of piano and violin music, but in the end we remember the defiant features of a woman who survived her torturers and devoted the rest of her life to dance. Here Gersht echoes Stanley Spencer’s emphasis on the integrity of individual memories and the way they can highlight the overwhelming extent of human tragedy in war.

• Catalyst: Contemporary Art and War IWM North, Manchester, 0161 836 4000, www.iwm.org.uk, until 23 February 2014
• Stanley Spencer: Heaven in a Hell of War Somerset House, London, 020 7845 4600, www.somersethouse.co.uk, until 26 January, 2014; Pallant House Gallery, Chichester, 01243 774557, www.pallant.org.uk, 15 Feb–15 June, 2014