Depression/WWII was the crisis 4 generations ago. Every 80 years (approx 4 generations) a new crisis appears. We are in our crisis NOW.
For more, read Strauss & Howe's book, "The Fourth Turning." There are even some free PDFs around, but the Kindle version is cheap.
I would say: 1. First Civil War. 2.Great Depression/ World War 2. 3. JFK assination Thur Reagan. 4. Now.