Complex sentence: On April 10, Francesco sent a letter to Philip II of Spain asking for permission for Eleanor and Vincenzo to be married, although Francesco also wished for proof of his son-in-law's fertility before concluding marriage negotiations.
Split into simpler sentences: On April 10, Francesco sent a letter to Philip II of Spain asking for permission so that Eleanor and Vincenzo could be married. However Francesco also wished for proof of his son-in-law's fertility before concluding marriage negotiations.