Complex sentence: Alexander was the younger twin of Berthold Schenk Graf von Stauffenberg who along with the youngest brother Claus Schenk Graf von Stauffenberg led the July 20 Plot against Hitler in 1944.
Split into simpler sentences: Alexander was the younger twin of Berthold Schenk Graf von Stauffenberg. Berthold, along with the youngest brother Claus Schenk Graf von Stauffenberg, is known for leading the July 20 Plot against Hitler in 1944.