For an intereſting third, deleted caſe of 'S' I preſent to you: ſ (the long-s).
"The sound written with ss, which goes back to an inherited Germanic /s/, differed from the sound written with sz; the ss was pronounced as a voiceless alveolo-palatal fricative [ɕ], whereas the sz was pronounced as a voiceless alveolar fricative [s]. Even when these two sounds merged, both spellings were retained. However, they were confused because no one knew anymore where an sz had originally been and where an ss had been."
I hate you both.