cases of wine would be sufficient for your occasion.
100 guests x 4 hours x 1 glass/hour = 400 glasses.
then, you take the 400 wine glasses and divide it by five glasses that you find in each bottle. you will get 80 bottles of wine. and, if you wanted to make sure that both wine lovers are taken care (red and white lovers), you can divide the 80 by 2 to get 40 bottles of red and 40 bottles of white.
if you have figured out that you need 80 bottles of wine for your 4-hour wedding for 100 guests, you will then need to figure out how many cases you will 