Complex sentence: This matter of taking offense over the content of the picture was a reasonable one because the film was within living memory for audience members because the war had ended 45 years, but members in the Grand Army of the Republic still exceeded 200,000 persons in 1910.
Split into simpler sentences: This matter of taking offense over the content of the picture was a reasonable one because the film was within living memory for audience members because the war had ended 45 years prior. The movement and influence of members in the Grand Army of the Republic was strong and memberships still exceeded 200,000 persons in 1910.