Joel 2 Verses 3-5

Before them fire devours,
behind them a flame blazes.
Before them the land is like the garden of Eden,
behind them, a desert waste—
nothing escapes them. 

Reminds me of:

Revelation 11:5 

If anyone tries to harm them, fire comes from their mouths and devours their enemies.

This is how anyone who wants to harm them must die.

There will be no escape from this army of God.

None.

For me the symbolism of all that is destroyed is, the pointing out that the earthly things don't matter and that it's the heavenly things which man has turned away from that should be held in higher esteem than what they are during this time. Repent, judgement is near, all you have had you have lost, don't you see how foolish it is/was to put your hope and faith in the things of this world?

They have the appearance of horses;they gallop along like cavalry. 

They are not horses this army.

 Again, it's figurative.

They have "the appearance" of horses. "They gallop a long like cavalry."

 In ancient times horses were feared instruments of warfare, kinda like the tanks of the day.

 An army coming with all it's horses?

 Like a tank battalion coming in modern times

"Let all who live in the land tremble, for the day of the Lord is coming."

Remember?

Revelation 9:7

 "And the shapes of the locusts were like unto horses prepared unto battle;

 and on their heads were as it were crowns like gold,

 and their faces were as the faces of men."

With a noise like that of chariots 

This is the noise of the lord so to speak.

There has been recorded history of locust plagues hitting an area and being heard as far as six miles away. You will not be able to not hear this army. They will make the lords pronouncements, judgement is at hand, repent, earnestly seek him, etc. No one will be able to escape this army or "the noise of the lord" they are bringing with them.

they leap over the mountaintops, 

No locust leaps over a mountain top. One of the reasons I see this army as being figurative. This army?

Supernatural in it's abilities, no one will be able to escape them, no one will be able to not hear the message of God they are to deliver.

like a crackling fire consuming stubble,  

Even the cut stalks left in the fields after harvest will not be immune from feeling the effects of this army so great will be it's power. Again, it's literary hyperbole to drive home a point. There is no escape from this army of the lord and it's message. Everything, even the stubble left in the field after harvest will feel it's affect.

like a mighty army drawn up for battle. 

Yeah they are.

"There are army's of you

there are army's of you

there are army's of you..."

just over and over that one night, tossing and turning in my sleep all night long.