Complex sentence: On May 29,1937, the Republican air force attacked Nationalist air bases and the port of Ibiza, the German pocket battleship "Deutschland", which was part of the International Non-Intervention Committee Patrol entered the area of the port to threaten the Republican planes.
Split into simpler sentences: On May 29,1937, the Republican air force attacked Nationalist air bases and the port of Ibiza. The German pocket battleship "Deutschland", which was part of the International Non-Intervention Committee Patrol entered the area of the port to threaten the Republican planes.