My uncle was a medic in Vietnam in the 60s when numbers were small. He told me stories about how they'd handle the clap out in the field, because it took a couple of weeks to set in so by the time symptoms would arrive, guys were in the field. They did not have 'the rod' yet.
They had only a field table to work with, so they'd lay out a towel while one medic placed the infected member on the towel and pretended to examine it. The other guy would roll up some manuals and sneak up behind the guy and WHAM smack the infection out. He said most guys passed out from the pain, but that 'procedure' made it treatable with pills from there on out.