Complex sentence: In August 1934, he led the Sixth Army Group out west of the Jiangxi Soviet as pathfinders for what was to become the Long March, subsequently joining forces troops under He Long to become the Second Front Army.
Split into simpler sentences: In August 1934, he led the Sixth Army Group out west of the Jiangxi Soviet as pathfinders for what was to become the Long March. The Sixth Corps subsequently joined forces under He Long to become the Second Front Army.