Complex sentence: Hindenburg retired from the army for the first time in 1911, but was recalled shortly after the outbreak of World War I in 1914 and first came to national attention at the age of 66, as the victor of the decisive Battle of Tannenberg in August 1914.
Split into simpler sentences: Hindenburg retired from the army for the first time in 1911, but was recalled shortly after the outbreak of World War I in 1914. He first came to national attention at the age of 66 as the victor of the decisive Battle of Tannenberg in August 1914.