War Horse presents the First World War as a catastrophe that wastes lives — human and animal — on both sides. The novel avoids assigning blame to one nation, instead showing the shared humanity of soldiers from different countries.
The bond between Joey and Albert — and between Joey and the various humans who care for him during the war — is the novel's moral centre. Loyalty is presented as a form of love that transcends language and circumstance.
Joey is wholly innocent — he cannot understand why the war is happening. His innocence makes the horror of his experiences all the more affecting for the reader.
The scene where a British soldier and a German soldier cooperate to free Joey from barbed wire is one of the most powerful in the novel. Morpurgo shows that ordinary people on both sides shared the same compassion.