I don't know who would be the best candidate for the inventor of propaganda, but Gustav II Adolf ran a large-scale propaganda campaign in Germany 1630-1632, describing himself as the Lion from the North coming to save the protestants of Germany from Imperial and Papal oppression, using old prophecies about a Lion laying the Eagle low - the Lion being him, as the Swedish royal coat of arms contains the two Folkunga lions the Eagle being the double-headed eagle of the House of Habsburg.

The ancient Egyptians were very good at propaganda and many (or maybe all?) pharaohs used it where they could to bolster their legitimacy to rule.

I would argue no, that he wasn't the inventor of propaganda, perhaps the author meant he was very effective in the use of it. From what I have been read and taught, Alexander the Great is one of the first people to use propaganda in an effective scale and propaganda does come up frequently in Late Roman Republic and Early Imperial historical discussions.

Regarding French Revolution era propaganda, I would argue that David was more instrumental with his art work (Napoleon Crossing the Alps, The Death of Marat) and earlier. But really I think the term came from the 17th century with Pope Gregory XV.

I would point out that [Beer Street vs. Gin Lane] (http://en.wikipedia.org/wiki/Beer_Street_and_Gin_Lane) was a pretty early form of public propaganda against the poor and the proliferation of unregulated alcohol called gin (although it was very different from the William of Orange Dutch courage gin). However, I don't know if this is the earliest instance. This was the subject for my undergrad thesis, so it is the era with which I am most familiar.

Hm, it really depends on how you define propaganda. Certainly Napoleon used grandiose, stylized art to sway public opinion and to increase his own cult of personality, but how many people would see it? I'm a twentieth-century historian, and I would argue you can't have propaganda until you have mass culture. That means a highly developed infrastructure with communication lines that make it possible to communicate the same ideas to a huge audience. It's not really possible to have propaganda before the industrial revolution. So how are you (or the author you read) defining propaganda?

I doubt it.

The advent of the printing press in the 15th century (in Europe, at least) really helped to spread the idea of propaganda, as religious or political ideology could be transferred to text and image, and mass produced via the printing press for circulation among the populace.

A good example of this from a British perspective is Foxe's Book of Martyrs (1563) a book concerned with recording the sufferings of Protestants at Catholic hands. This martyrology was a best-seller of the time and its grisly images and descriptions of Protestant suffering helped influence popular opinion regarding Roman Catholics.

Later on, pamphlets, cartoons and so-called news sheets were employed extensively in the English Civil War (1640's) by both sides to demonize their rivals, play up victories and try to turn popular opinion. The Royalists had their own regular news sheet (basically a precursor to a modern newspaper) called Mercurius Aulicus, I believe the Parliamentarians had a similar publication but I'm afraid the name escapes me at the moment.

Having said all this, I feel fairly sure that propaganda has been used for thousands of years. The arrival of the printing press however, allowed propaganda to be spread among the public to a greater extent than ever before, exposing them to new ideas and concepts, even if they could not read.