How Did the Letters I and U Work in English?

The letters I and U were such a problem for scribes in the Middle Ages. When one of those letters appeared beside the other, or beside an M, or an N, or an L, it just looked like a bunch of vertical lines. It was difficult to tell where one letter ended and another began. As we'll see, medieval scribes came up with a variety of solutions to deal with that problem. And those solutions shaped the way those letters work in English to this day.