In the earlier chapters Sun Tzu said to take the place and the time first. The chapter on the contest of armies goes into how you actually take that place.
The hardest problem is this. You and the other side are moving toward the same destination. Yet hurry to arrive first and you arrive late, or arrive exhausted.
軍爭之難者，以迂爲直，以患爲利
jun zheng zhi nan zhe, yi yu wei zhi, yi huan wei li
What is hard in the contest of armies is taking the roundabout road as the direct one, and turning trouble into advantage. (The Art of War, Contest of Armies, translated directly)