This year marks the 20th anniversary of the fall of the Berlin Wall. Deutsche Welle has a succinct article about the Leipzig pastor who organized peaceful prayer gatherings at the time. This event showcases the two kingdoms of God and how He uses both to accomplish His means. A book entitled ,,Rebuilding a House Divided" by Hans-Dietrich Genscher looks at how the U.S. Secretary of State and the European Foreign Ministers helped bring about the reunification of Germany. It's a good book; I read it about ten years ago.
Here's the DW article.