Sforno on Exodus 14:19/ספורנו על שמות י״ד:י״ט

1ההולך לפני מחנה, in the column of fire.

2וילך מאחריהם, in order to (melt) dissolve the very chunks of water which had frozen in order to enable the Israelites to cross on a dry seabed, and to turn the seabed into a slimy mass which would spell doom for the Egyptians. At this juncture there was no need for the pillar of cloud to be at the head of the marching Israelites. The dry path in the water was their guide

3ויעמד מאחריהם. behind the Israelites and behind the column of fire.