And the Angel of God, which went before the camp of Israel, removed and went behind them… – Exodus 14:19

…the glory of the LORD shall be thy rereward. – Isaiah 58:8

The Angel of the Lord had removed, but it is added, He “removed and went behind them,” and He was just as close to them when He was in the rear, as when He led the van. He might not seem to be their guide, but He had all the more evidently become their guard. He might not for the moment be their Sun before, but then He had become their Shield behind. “The glory of the Lord was their reward.” The Lord may be very close to thee, dear child, when thou canst not see Him, perhaps closer than ever He was when thou couldst see Him. The presence of God is not to be measured by thy realization of it. When thou canst not tell that He is with thee at all, and thou art sighing and crying after Him, those very sighs and cries after Him are the holy fruit of His secret presence. It may be, the day shall come when thou shalt think that He was more near thee when thine eyes were filled with weeping after Him, than when thou didst take thine ease, and speak confidently.

That glorious Angel, shrouded in the clouds, stood with His drawn sword in the rear of Israel, saying to Pharaoh, “Thou darest not come further, thou canst not break in upon My chosen.” He lifted up His vast shield of darkness, and held it up before the tyrant king, so that he could not strike, nay, could not see. All that night his horses champed their bits but could not pursue the flying host. “They were as still as a stone till Thy people passed over, O Lord, till Thy people passed over whom Thou hadst purchased.” It is glorious to think that the Lord stood there, and the furious enemy was compelled to halt. Even thus the Lord remaineth with the dear child of God. Thou canst not see anything before thee to make thee glad, but the living God stands behind thee to ward off the adversary. He cannot forsake thee… He standeth fast as thy rock, steadfast as thy safeguard, sleepless as thy watcher, valiant as thy champion. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/1793.cfm