In Classical Latin, the letter C was always hard, never soft. (The same goes for the letter G.) In Church Latin, the letter C is palatalized (turns into a Ch sound) when followed by ae, oe, e, i, or y, but is still supposed to be hard otherwise. Similarly, the letter G is soft (like J) before front vowels. (The Ecclesiastical pronunciation was standardized in the 19th century, based on contemporary Italian pronunciations. Before that, Churchmen tended to pronounce Latin like they did their native languages, which could cause all kinds of confusion. Ecclesiastical pronunciation is much better than the traditional English pronunciations of Latin, but can still be a bit confusing. The big problem is not the palatalization, but the fact that the diphthongs AE and OE are both pronounced the same as the letter E. It can be hard to guess which is being used, which can significantly change the meanings of some words. You don't get such confusion in Classical Latin, where the sounds are very distinct.) In Archaic Latin, the letter C (which was derived from the Greek Gamma) was pronounced like the letter G (/g/). By the 3rd century, the letter K (derived from the Greek Kappa) was falling out of favor (although it continued to be used, at least when followed by the letter A, to transcribe foreign words or sometimes just make something seem exotic) and the letter C came to be used for both sounds. The (/g/) and (/k/) sounds were practically used in free exchange for a while, but the C (/k/) sound was more common. The letter G (called "C cum linea," or "C with a line") was a variant of C invented for cases when they wanted to be sure that the old voiced G (/g/) pronunciation was used. (The letter C continued to be used in abbreviations of words, mostly proper names, even after almost everyone used the letter G when writing them in full. For example, C. denoted the praenomen Gaius and Cn. denoted Gnaeus. I believe that C also remained more common on public engravings while G was used more in manuscripts.) Historical accounts credit Spurius Carvilius Ruga (a former slave who around 230 BC started the first school in Rome that was open to the public for a modest fee) with inventing the letter G (perhaps because he got tired of people mispronouncing his name, which was written RVCA), but some archeological evidence shows it was occasionally used before his time. He may have popularized its use though, or perhaps been the first to consider it a distinct letter rather than treating the line as a diacritical mark. He is said to have eliminated the letter Z from the Latin alphabet in order for the new letter to have a place in the alphabetical order. (Z was never used in native Latin words, and some say the Censor Appius Claudius had already expunged it from the list.) Z was borrowed back from Greek centuries latter, once transcribing foreign words became more important. The letter Y ("I-Graeca" or "the Greek I") had already been introduced by then. Caesar was probably pronounced with a G sound originally, but I'm pretty sure it had a hard C (so it was pronounced like the Gernam Kaisar) by the time of C. Julius Caesar. It is possible that some rustic dialects retained the G sound though, as they tended to be more conservative.