Conversation so far:
How did Calamity Jane get her nickname?
Jane was involved in several campaigns in the long-running military conflicts with Native Americans. Her claim was that: It was during this campaign that I was christened Calamity Jane.
What campaign did Calamity Jane gain the name from?
Calamity Jane gained her nickname in the 1872–73 campaign

Question: Why was she given this nickname?
Self-contained rewrite: Why was Calamity Jane given this nickname?