Firelock Armed Citizenry crushes all 120 Swiss Guards

[British HMS Victory]

I was playing as Prussia, I recently captured a region and soon only 2 regiments of Firelock Armed Citizenry appeared. So then France invaded that region with one regiment of Swiss Guards. The first regiment of Firelock Armed Citizenry routes while being shattered after 14 deaths and only 2 kills. So the 2nd regiment of Firelock Armed Citizenry prepared for the worst, there was no fort. I was freaked out and slowed down the game as this could be frightening. The first volley was by the Citizens. They managed to kill 31 Swiss Guards. Then the 2nd volley was by the Swiss Guards. They killed 23. The Citizens were not trained or have any experience plus they were alone. They still got another volley and took down 12. Then the Swiss Guards shot another volley, no kills. Then Citizens, 2 kills. Then Swiss, 7 kills. Then Citizen 22. Soon the began to route for some reason (they were resistant to morale shocks). And my Citizens manage to get 2 volleys on them, killing all of the remaining ones. I was surprised and quickly trained troops because they had Swiss Guards already. I still wondered "How did they kill all the Swiss Guards?"
Please explain.

[poa]

what difficulty are you on ?
i just had a similar battle, my 2 citizens in buildings vs AI 1 infantry + 1 general,
my first citizen killed 11 before being routed, my 2nd citizen & general in the next building didnt fire at all,
was shot at for a while and eventually stormed

[Rijul.J.Ballal]

What difficulty were you playing on? The effectiveness of your units depends on your difficulty setting.