What is associated with: constantinople was the meeting point in 1097 when 4 european armies launched the first of these?

What is referred to by 'constantine xi'? Based on the clue 'constantines mother st helena is most famous for s...', what is the answer? Based on the clue 'constantinople gained strategic importance due to ...', what is the answer? What is associated with: constantinople officially became this city in 1930? Based on the clue 'constellation depicted with 5 stars on the flag of...', what is the answer? Based on the clue 'constellation on papua new guineas flag the countr...', what is the answer? What is referred to by 'constellation seen here'? Based on the clue 'constitution hall in washington dc is part of a 3 ...', what is the answer?