I see what you mean...

I'd be tempted by the Broad Street Pump incident. Or maybe Anton van Leeuwenhoek's observation of single celled organisms. Or Semmelweis and the theory of surgeons washing their hands.

Maybe even Jenner's study showing cowpox could be used to immunise against smallpox?

And now I'm REALLY going to close all the open wikipedia pages... *sigh* To prove a point: I've also read about the sinking of the HMAS Sydney, too...