The work was written to commemorate Eugen Schauman who had in 1904 shot Governor-General Nikolay Bobrikov and then killed himself.

[4] Sibelius mentioned on New Year's Day of 1905 "that he intended to write a requiem in memory of Eugen Schauman and that he had already started to work on it.

The work in sonata form is introduced by the violins and violas, with a main theme developing "like the approach of a distant cortege".

[4] In its revised form, In memoriam is scored for the following instruments,[6] organized by family (woodwinds, brass, percussion, and strings): The original version of the piece called for 1 piccolo in addition to the orchestra forces above.

[7] The British conductor Sir Thomas Beecham and the London Philharmonic Orchestra made the world premiere studio recording of In memoriam in 1938 for His Master's Voice (HMV).