Advances

In the posting on antibiotics, it was noted that the initial discoveries were at the very end of the Unraveling and the start of the Crisis. They were in production soon enough that they were available in large amounts by the peak of the crisis a few years later -- 12 years for penicillin, less than 10 by any count for the sulfas. 

Meanwhile, a few months Mark Andeesen noted that smartphones are going to be available everywhere within a few years - again, right around the expected peak of the Fourth Turning. The first smartphones were the BlackBerry variants around 2003 but it was when the iPhone came out in 2007 that they really became an item available to the masses. In either case, though it can be seen as an advance from the tail end of the Unraveling. 

How could we better confirm that these might be analogous? We could look at other similarities and differences. We could see what predictions were made for antibiotics after their initial discoveries. We could identify other tech that made a difference in previous Crisis periods. 

The longbow - while it made a difference, certainly, in English history -  isn't a matching example.   It was available for hundreds of years before and for much of the Hundred Years' War, including Crécy in 1346, almost 70 years before Agincourt.