Here are some one liners...
The Gutenberg Press Changes Everything -- It makes books cheaper and faster to produce. By modern standards it is as slow as snails but compared to hand copying, it's a miracle. I also talk about Kindle ebooks.
The Beginnings of a Professional Military -- The King of France has passed an ordinance to establish, organize and pay for a small standing army. It won't work out at first but eventually its going to catch on.