Caesar and caesura

Caesar and caesura are two similar-sounding Latin words which have made their way into English unsullied in terms of their orthography. The same can however not be said of their pronunciations. The original Latin pronunciations of /kaisar/ and /kaisuːra/ have evolved into /siːzər/ and /sizjʊrə/ respectively. Why/how did this come to pass? Furthermore, why does Caesar have the long /si:/ while caesura doesn't?

Solution 1:

For a complete answer, take a look at the Wikipedia article on the traditional English pronunciation of Latin or at Appendix B ("The pronunciation of Latin in England") of Sidney Allen's Vox Latina: The Pronunciation of Classical Latin. The rough story seems to be that the traditional English pronunciation of Latin consists of the (Norman?) French pronunciation of Latin at the time of the Norman Conquest, filtered through the sound changes undergone by English (including the Great Vowel Shift), but with some peculiarities of its own. If I'm reading things correctly, it would seem that the differing pronunciations of ae in Caesar and caesura essentially stem from the fact that the ae in Caesar is accented, whilst the ae in caesura is unaccented (and followed by a single consonant), and was thus "reduced" (i.e., shortened and opened?) in the English pronunciation.