he did not conquer any countries in 52 BCE. in 51 BCE he completed his conquest of Gaul.
pliny the elder credits him with 50 battles before he went to Gaul 58-50bc he won the corona civica in a seige in asia minor and went to spain aas a pro-preator and fought there its not known how many,during the Gallic wars we know of some major battles he fought in because of the Gallic wars battle of arar 58bc against the helvetti battle of Bibracte 6 legions vs up to 368,000 battle of vosges against the german war lord Ariovistus 30,000 vs 70,000 battle of axona caesar had 50,000 belgic confideration up to 360,000 siege of Avericum 52bc battle og Gergovia 52bc siege of alesia 52 bc 40,000 men vs 320,000 gauls in 54-53 he landed in britan and fought there and crossed the rhine into germany
Fifty-fifty: a big part of the country got invaded, but the Romans were stopped by Vercingetorix in Alesia 52BC. So they were not as good as the Romans (who had a massive army), but not that bad either. Also, a part of France was Celtic until approximately the 6th century, and the celts are supposed to have been very scary warriors.
There is evidence of early settlements in the region from 4200BC. The Romans conquered the area in 52BC and created a permanent settlement. After the Romans the Germanic Franks made the city their capital. Later, the Persians built a fortress there and even later the place was destroyed by the Vikings. Paris slowly recovered and became a capital once more developing onto the place we know today
At that time, the Romans used a lunar calendar of about 354 days. As a result, intercalary months have to be inserted every so often to keep the calendar roughly on tract with the seasons (just like the Jewish calendar today). Since 52BC only 1 intercalary month had been inserted leading to the effect that by 46BC the calendar was off by 67 days. To correct the calendar to get it back to the vernal equinox occurring on (or about) 25 March, 2 intercalary months (of 33 days and 34 days) were inserted between November and December 46BC making the year 445 days long. Caesar then did the calendar reform which upped the days of the months to get the year to 365 days with a leap year every 4 years (starting 1 Jan 45BC) - the Julian calendar which was then later refined into the Gregorian calendar to correct for the leap years by making centuries leap years only if evenly divisible by 400.