Complex sentence: It took the French a month to complete their preparations for the campaign, but by the end of January 1885, Brière de l’Isle had assembled an expeditionary column of just under 7,200 troops, accompanied by 4,500 coolies, at Chu.
Split into simpler sentences: It took the French a month to complete their preparations for the campaign. By the end of January 1885, Brière de l’Isle had assembled an expeditionary column of just under 7,200 troops, accompanied by 4,500 coolies, at Chu.