The Piano Concerto No. 5 in B flat major, H 366, also known as Fantasia concertante, is Martinů's last solo work for this instrument. It was written in Schönenberg (near Pratteln) in Switzerland between September 1957 and January 1958. The three-movement concerto is dedicated to pianist Margrit Weber, who gave its first performance on 31 January 1959 with the Berlin Radio Orchestra under the baton of Gotthold Ephraim Lessing.
From 1957 to 1959 Martinů found refuge at the residence of Maja and Paul Sacher in Schönenberg. He knew that he could not return to his homeland for political reasons, and perhaps this is why his last compositions, especially, are so full of the spirit of his native Bohemian-Moravian Highlands. On 4 July 1957 he wrote to Paul Sacher: "But I don't see my future in rosy colors; I'm beginning to fear that I will never find peace and will not be able to return to Prague, which would be the best solution for me." He gave the reasons in another letter, of 22 July 1957, to his friend Frank Rybka in America on the occasion of an upcoming trip by Rybka to Bohemia: "Explain to them at home that if I appeared there great propaganda would be made from it - that I approve of the regime and so forth." This torn state of mind is reflected very precisely in the Fifth Piano Concerto, especially in its opening movement.
The work was written between the second and third orchestral Parables, H 367, and its premiere, set in advance, resulted in the postponement of major revisions to the opera The Greek Passion, H 372. Although the concerto bears the subtitle Fantasia concertante, it is written in the classical three-movement form: rather than a free fantasy form, the word "fantasia" refers to the fantastical, fanciful motives with which Martinů works. The opening theme of the first movement, Poco allegro risoluto, seems mildly neurotic, whereas the second theme has almost naive suggestions of folk music and the tender lyricism of the "Highlands". This latter mood is further developed in the second movement, marked Poco andante, which begins with a solo in the clarinet. The solo is passed to an oboe and a trumpet, which together with delicate strings subtly prepare the first purely solo entrance of the piano. This music does not deny its inspiration from impressionism, as evidenced not only by the major share taken by wind instruments in the orchestral color of the second movement but also by the thematic and harmonic work. The third movement, Poco allegro, forms an emotionally-volatile close to the whole work, which lasts more than twenty minutes. The opening dynamic motion in sixteenth notes does not bear any striking theme. Such a theme appears roughly a third of the way through the movement in the solo piano supported by solo clarinet and is then elaborated rhythmically in the full orchestra. In this movement, the solo piano part is conceived as a virtuoso toccata. In the whole work, as in other pieces by Martinů, the harmonic relations are free: keys interpenetrate each other, and the composer offers various modulatory surprises.
Lenka Foltýnová, programme of the Bohuslav Martinů Festival's concert, December 19–20, 2002