Charles Ellicott Commentary Numbers 14:44

"But they presumed to go up to the top of the mountain: nevertheless the ark of the covenant of Jehovah, and Moses, departed not out of the camp." — Numbers 14:44 (ASV)

They presumed to go up. — that is, they made a bold attempt to ascend the mountain. Their enemies appear to have encountered and defeated them before they had actually gained the summit.