13 And Jehovah said unto Moses, Rise up early in the morning, and stand before Pharaoh, and say unto him, Thus saith Jehovah, the God of the Hebrews, Let my people go, that they may serve me.
14 For I will this time send all my plagues upon thy heart, and upon thy servants, and upon thy people; that thou mayest know that there is none like me in all the earth.
15 For now I had put forth my hand, and smitten thee and thy people with pestilence, and thou hadst been cut off from the earth:
16 but in very deed for this cause have I made thee to stand, to show thee my power, and that my name may be declared throughout all the earth.
Exodus 9:13-16; ASV
Why did Jehovah plague the Egyptians?
1. To communicate to them that He is incomparable.
2. To communicate to them that He is omnipotent.
3. To make His name known in all the Earth.
Jason Cicero