Ernest Newman suggested that the music of Titurel's Funeral Procession had its origins in a sketch to be found in Wagner's occasional diary, the Brown Book, dated 7 May 1868. It was originally intended for a funeral march for Romeo and Juliet. Later, after the Franco-Prussian war of 1870-1, Wagner had thought to write a symphony for the fallen, possibly based on this sketch. But the composer was discouraged by the administration in Berlin, and nothing came of it, although he returned to the idea several times.
Although Newman misquoted the first bar of the sketch, possibly from an inaccurate copy of the page from the then unpublished diary, there are similarities (in both cases, there is a repeated figure (a)) between the Romeo and Juliet march and the funeral music in Parsifal.
Funeral Procession