It is common knowledge that there are generally no “launch dates” for letters of our alphabet. They just evolve. The shapes and sounds develop slowly over a long period of time. The letter G, however, is an exception, making its official debut sometime in 312 B.C, but our story begins earlier than that.
The Phoenicians used a simple graphic form that looked roughly like an upside-down V to represent the consonant ‘g’ sound (as in “go”). They named the form gimel, which was the Phoenician word for camel. Some contend this was because the upside-down V looked like the hump of a camel.
The Greeks borrowed the basic Phoenician form and changed its name to gamma and made some dramatic changes to the letter’s appearance. At various times in ancient Greek history, the gamma looked like a one-sided arrow pointing up, an upside-down L, or even a crescent moon, but the gamma always represented the same hard ‘g’ sound that it did for the Phoenicians.
This Greek form was adopted by the Etruscans and then again by the Romans, where for many years it represented both the hard ‘k’ and ‘g’ sounds. This brings us to 312 B.C., when our modern G was formally introduced into the reformed Latin alphabet. The G was created to eliminate the confusion caused by one letter representing two sounds. The basic shape, which now looked like our C, was used to represent the sounds ‘s’ and ‘c,’ and a little bar was added to create the letter G, which denoted the guttural stop ‘g.’
And it seems the order of the Roman alphabet was felt to be such a concrete thing that a new letter could only be added in the middle [...]