Complex sentence: After Fredericks early death in October 1918, his brother Alexander J. Dickie succeeded him, eventually becoming the magazines longest serving editor by continuing in the role until 1946, before becoming consulting editor until his retirement in 1948.
Split into simpler sentences: After Fredericks early death in October 1918, his brother Alexander J. Dickie became the magazines editor. A. J. Dickie would become the magazines longest serving editor, continuing in the role until 1946 and remaining as consulting editor until his retirement in 1948.