Described as ‘testamentary’ on its back cover, the latest release in Harmonia Mundi’s Debussy anniversary series is perhaps more an act of commemorative reflection than an overt celebration of his genius. It gathers together, by no means for the first time on disc, the three sonatas, written between 1915 and 1917 as the First World War destroyed Debussy’s world and cancer slowly ravaged his body. They’re framed and separated here, however, by his four last, rarely heard piano pieces, all of them ostensibly pièces d’occasion, though they’re linked by a deep, sometimes despairing sadness that reveals much about the anguish of his final years.

Three of them formed his contribution to the war effort. The sombre Berceuse héroïque was commissioned, along with pieces by Saint-Saëns, Mascagni and Elgar, by the Daily Telegraph for inclusion in a volume entitled King Albert’s Book, published in support of the beleaguered monarchy of occupied Belgium. The manuscript of Élégie pour piano was intended to be sold to raise money for war relief, while Page d’album was written for performance at a charity concert for ‘Vêtement du blessé’ (‘Clothes for the wounded’), for which his wife worked as a volunteer. The saddest of the four is Les soirs illuminés par l’ardeur du charbon, Debussy’s last work for piano, written during the bitter winter of 1916 17 as a gift to his coal supplier, one M Tronquin, in the hope that the latter would furnish him with enough fuel to keep warm.

Juxtaposed with the sonatas, they throw into relief the ambiguities of the latter, with their mixture of retrospection, fantasy and innovation. The Sonata for flute, viola and harp sounds more than ever like a final, nostalgic evocation of the worlds of Faune and Bilitis here: the performance is relaxed, fractionally too much so in the first movement, perhaps, but it tingles with sensuousness and the shifts in colour are all beautifully realised. Isabelle Faust and Alexander Melnikov’s account of the Violin Sonata, Debussy’s last completed score, embraces exquisite fragility and strength in equal measure, the finale gathering itself for one last moment of assertion at the end. Jean-Guihen Queyras and Javier Perianes’s performance of the Cello Sonata, noble in manner and grand in scale, balances the austere grief of the opening movement with understated wit in the Sérénade and nervous energy in the finale. Tanguy de Williencourt, meanwhile, binds the disc together with the four piano pieces, played with admirable restraint and quiet, if unsparing intensity. Listen to it in a single sitting, and in the right playing order: it’s extraordinarily moving.