Numbers 10:34

And the cloud of the LORD was upon them by day, when they went out of the camp.

The cloud of the Lord was upon Israel by day when they went out of the camp, marking His presence with them and guiding their travels through the wilderness. Its lifting was the signal that they were to journey, while its resting over the tabernacle was the signal that they were to remain encamped. The ark of the covenant went before the people on their journey. They traveled in ordered tribes, each under its own standard.

As the ark set forward Moses called on the Lord to rise up and scatter Israel's enemies, and when it rested he called on the Lord to return to the many thousands of Israel. After three days' journey from Sinai the direction of the march was fixed by the guiding cloud, and Moses was following that cloud just as the people were. Displeasure with the direction of the march and faultfinding with the way Moses was leading were therefore done with full knowledge that Moses was not choosing the course himself but was following God's guidance. The complaining began with the mixed multitude, who were not fully united with Israel and were ever watching for cause for censure, and dissatisfaction with God's leading is contagious and soon spread through the camp.