August 6 is the anniversary of the atomic bombing of Hiroshima. August 9 is the anniversary of the atomic bombing of Nagasaki.
One year in South Bend we held a Nagasaki commemoration and our signs were confusing to passersby. A short, clear sign might be NAGASAKI / 1945 / MOURN THE DEAD.
Here’s a leaflet with a Catholic focus you can customize.:
If you have constructive suggestions, or this info is helpful, please post a comment.