Complex sentence: The increasing need to defand against attack from the air led to a number of Territorial Army units being converted to the anti-aircraft role in the 1930s and a major reorganization in 1938 saw the TA divisions reduced from twelve to nine battalions.
Split into simpler sentences: The increasing need to defand against attack from the air led to a number of Territorial Army units being converted to the anti-aircraft role in the 1930s. A major reorganization in 1938 saw the TA divisions reduced from twelve to nine battalions.