Where did the largest battle in the struggle between the mexican
military and the french take place? why did it start in this city? why was
the battle between the mexicans and french so important?

The largest battle took place on May 5 1892 near the city of Puebla. It happened there, because the French soldiers mistakenly thought they should march to sea side and the Mexicans understood it is a hostility, so the confrontation was just a matter of time. The French decided to have the confrontation near Puebla, as they believed people in there to be friendly to them. It was an important battle because it provided a morale boost to the Mexican side.

Nationalism created a standoff between countries trying to prove who was better. This increased tension boiled over until Archdule Franz Ferdinand was killed.