Prokofiev began writing Piano Sonatas Nos. 6, 7, and 8 concurrently in 1939. This suggests that from the outset, these works possessed a unified structure. Perhaps reflecting this intention, these works are referred to as "War Sonatas" in Japan, while in his native Russia, they are more neutrally called the "Triad (Triada)". It is said that in these works, the intense sharpness and dynamism of his early compositions blend with the lyricism, theatricality, and classical forms and styles of Prokofiev's mature period. His close friend, the composer Myaskovsky, described this as "a mixture of the old and new Prokofiev."

To what extent are elements of war—in this case, World War II, known as the "Great Patriotic War" in Russia—incorporated into these untitled absolute music pieces, the "Piano Sonatas"? Answering this question is, in fact, difficult. It is certainly true that elements of war influenced the reception and evaluation of these sonatas both within and outside Russia, as well as Prokofiev's own creative environment. However, his contemporary Richter stated in his memoirs that "the war began" in 1941, and Prokofiev's friend and biographer Nestyev also expressed a similar view. From the perspective of these contemporaries, the connection between the conception of this series of sonatas in 1939 and the war is tenuous (especially concerning the Sixth Sonata, which was already completed in 1940). While the factor of war, which is greatly related to intensity, cruelty, and atrocity, is an important interpretation, when interpreting these large-scale compositions, attention must also be paid to other elements—such as their purely musical structure and style, what was involved in their creative process, how the premieres took place, and the fact that themes in some movements were repurposed from other works.

The composition of the Sixth Sonata, though interrupted by a radio commission in October 1939 for a large-scale cantata, Zdravitsa (Toast), celebrating Stalin's 60th birthday, was completed on February 11, 1940. Its radio premiere by Prokofiev himself took place on April 8 of the same year. The concert premiere was given by Sviatoslav Richter on October 14, 1940. It is said that for Richter himself, this concert marked a memorable step as he embarked on his career as a professional pianist.

First Movement (Allegro moderato)

A minor, 4/4 time. In sonata-allegro form.

The powerful first theme is primarily characterized by a descending motif in parallel thirds and an accompaniment of dynamic leaps, while the sharp rhythms and tritones in the bass create a vivid impression of dissonance. In addition to the sound, the asymmetrical phrase structure further enhances the sense of instability. The transition section gradually releases energy, leading to the second theme. A simple melody, completely contrasting with the first theme and even conveying fragility, is presented in octave unison.

The large development section is contrapuntally constructed. The beginning centers on the opening three notes of the second theme (the C-D-F motif), but the articulation and dynamics are completely transformed, with no trace of the former lyrical atmosphere. From the middle onwards, fragments of the opening theme's parallel thirds motif appear alongside a subsidiary theme in its complete form, sometimes expanded, forming the climax of the movement. From this point, a motif primarily consisting of a descending triplet figure, based on the latter half of the second theme, is emphasized.

As if disproportionate to the scale of the development section, the recapitulation of the themes is extremely condensed. After the first theme, the second theme appears in its expanded form from the development section. Interspersed with elements from the recapitulation, the opening motif then appears alone, asserting itself and concluding the movement.

Second Movement (Allegretto)

E major, 2/2 time. In ternary form. A scherzo movement with a gavotte-like rhythm. The cheerfulness and elegance based on court dance are transformed into Prokofiev's unique, boldly humorous expression.

Upon reaching the middle section, marked Meno mosso, where the tempo slightly slows, the gavotte rhythm disappears, and expressive emotions fully emerge. The tonality and harmony are unstable and enigmatic, as if the main section's cheerfulness is distorted and dark clouds gather. After stabilizing in B-flat major, the main section returns. This recapitulation is brief, and the register gradually ascends to higher notes, moving towards the conclusion.

Third Movement (Tempo di valzer lentissimo)

C major, 9/8 time. A very slow waltz.

The theme begins and ends on the C major tonic chord, forming a long-breathed phrase. However, the abundant accidentals primarily in the inner voices make it sound as if it is not bound by functional harmony. In addition, the undulating motion of the inner voices and the thickness and breadth of the chords create a highly complex texture. As if drawn by this undulation, the C major theme modulates successively, building to a symphonic climax.

The middle section, marked Poco più animato and beginning with a ripple-like figure in the bass, creates a distinct and very rough development separate from the main section, bringing a multi-layered structure to the piece.

Fourth Movement (Vivace)

A minor, 2/4 time. Following the typical pattern of the final movement in a classical multi-movement sonata, it adopts rondo form.

The frequently recurring main theme is centered on a melody characterized by rapid sixteenth notes and a distinctive rhythm that responds to them. This main theme is skillfully connected with various episodes. The first episode is in C major, featuring a sparkling, lively melody in the high register, accompanied by triplet arpeggios, which catches the ear. The second episode appears in G-sharp minor, showing a repeated note figure combined in melody and accompaniment, and a sixteenth-note motion similar to that of the main theme.

In the third episode, the movement slows to Andante, and motifs from the first movement are recalled, beginning with the appearance of the first theme's descending motif in parallel thirds.

As soon as the rapid tempo returns, the second episode is recapitulated in A minor and the first episode in A major, both integrated with the main theme. The main theme reappears, accompanied by the descending motif in parallel thirds, then breaks down into perpetual motion, leading to a dissonant repetition of the same note played in triplets, concluding the piece with fervor.