Complex sentence: Saint Crispin is often associated with the Battle of Agincourt since the battle was fought on his feast day, and has been immortalised by Shakespeare's St. Crispin's Day Speech from his play "Henry V".
Split into simpler sentences: Saint Crispin is often associated with the Battle of Agincourt since the battle was fought on his feastday. It has been immortalised by Shakespeare's St. Crispin's Day Speech from his play "Henry V".