The fugue is considerably more difficult than the prelude primarily because it features imitative polyphonic writing for 4 highly independent voices. Nevertheless, it is within the reach of any organist with basic organ playing skills.
This composition starts out with the subject presented in the soprano voice in the key of D minor (the Tonic) which is followed by the tonal answer in the alto (A minor, the Dominant, measure 4).
The exposition continues with the subject entry in the tenor voice (D minor, the Tonic, measure 6) and the answer in the bass (A minor, the Dominant, measure 9).
In measure 12, we can see a head motive of the subject in the soprano voice in A minor (the Dominant) which leads to the cadence and subject entry in the alto voice in C major (the relative key of the Dominant, measure 14).
In measure 18, the pedals play the subject in F major (the relative key) after which we can find an ascending sequence (measures 21-24) formed by the head motive of the subject. This sequence moves through the keys of C major (relative of the Dominant), F major (relative key), G minor (the Subdominant), and A minor (the Dominant) and finally reaches the full-length subject in the alto voice in the key of D minor (the Tonic, measure 25).
As it is customary for many Baroque compositions, this fugue closes with an excursion to the Subdominant (G minor) which is presented by the subject in the bass part (measure 27).
I have prepared a score of this composition with complete fingering and pedaling written in which greatly facilitates practicing and learning process of this exciting work.
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