Complex sentence: The American fleet steamed, or sailed in some cases, back to the Havana, Cuba blockade, on May 18, Sampson learnt that Admiral Cervera's force had sailed to Santiago de Cuba.
Split into simpler sentences: The American fleet steamed, or sailed in some cases, back to the Havana, Cuba, blockade. On May 18, Sampson learned that Admiral Cervera's force had sailed to Santiago de Cuba.