Picking a round number of 200MM people in the world at the time [1], this is 0.1% of the entire population killed in a single event, which is staggering.<p>[1] - <a href="https://en.wikipedia.org/wiki/World_population_estimates" rel="nofollow">https://en.wikipedia.org/wiki/World_population_estimates</a>
The Dutch <i>National Geographic</i> article contains more detail and reads reasonably with computer translation:<p><a href="http://www.nationalgeographic.nl/artikel/genocidaire-slachting-onder-leiding-van-julius-caesar-bij-kessel" rel="nofollow">http://www.nationalgeographic.nl/artikel/genocidaire-slachti...</a><p>Regardless, the scale of slaughter is staggering.
You can read, Caesar's version here:
<a href="https://en.m.wikisource.org/wiki/Commentaries_on_the_Gallic_War/Book_4#1" rel="nofollow">https://en.m.wikisource.org/wiki/Commentaries_on_the_Gallic_...</a>
According to Caesar he made 430000 casualties, while historians now estimate it were about 160000. Among these were women an children. On the Roman side there were zero casualties so it was more a genocide than a battle.
Related: For curated list of the 100 largest atrocities, ranked by largest loss of life, check out Matthew White's <i>The Great Big Book of Horrible Things</i> [0]<p>It grew out of his website, <i>Historical Atlas of the Twentieth Century</i>, and while he is not an historian by profession (I believe he's a librarian), the book is very well researched (lots of footnotes, citations, etc.) and IMO, "fun" to read. (Only because of his style of writing, obviously not about the content)<p>Each event is a relatively short read, with decent background provided, though the book is quite long overall.<p>Spoiler: One of the items on the list is Caesar's Gallic Wars, and there are many dedicated to various events that transpired the Roman {Republic, Empire}<p>0. <a href="http://www.bookofhorriblethings.com/" rel="nofollow">http://www.bookofhorriblethings.com/</a><p>1. <a href="http://users.erols.com/mwhite28/20centry.htm" rel="nofollow">http://users.erols.com/mwhite28/20centry.htm</a>