Complex sentence: To keep them from interfering with other camp meeting activities, the day was moved to the Tuesday before the official start of the meeting in 1886, but in 1889, it was moved to the first Wednesday.
Split into simpler sentences: To keep them from interfering with other camp meeting activities, the day was moved to the Tuesday before the official start of the meeting in 1886. In 1889, it was moved to the first Wednesday.