Rashi: He used to raise troops around him like a river, to flood around him. Radak - this is said mockingly (he no longer does so).

Radak (8, citing Targum Yonasan): He goes out with his camps like a cloud goes out and covers the land.

Malbim: When the Nile ¹ rises, it covers the entire land with its abundance of water. So Egypt covered the land with its great camps.

Rashi citing Targum Yonasan: Its waters will be turbulent.

Malbim: Just like a flowing river, its water is sharp and it washes away everything in its path, so Giborim [of Egypt] used to inundate all kingdoms.