The Story of Gideon is told in Judges chapters 6 an 7.
In the legend, Israel is a downtrodden nation beset by Midianite invaders.
Gideon is inspired by a divine visitation to unite the nation and drive off the Midianites, 
though God insists that he only has a 300 man army; "least he should claim the credit himself".
Gideon succeeds in defeating the, much larger, Midianite army, and kills their leaders.
Despite rejecting a ruler's title, he then rules, effectively,  for many peace-filled years.
The  people worship a golden ephod that he had created using the money that he made through his victory.
His illegitimate son takes over after him, and, swiftly slaughters all other contenders,
 rules badly before being ousted, and killed, by a rebellion.
 
A more likely tale is that Israel has been trying to run their own kingdom, free of the Egyptian Empire.
and maybe rejected, or ignored Pharoah's massages   (“Israel did wrong in the eyes of the Lord”).
As a result,  Pharoah withdrew his protecting border forces.
(perhaps they even demanded that he did so).  

The Midianites, who lived in the mountainous desert to the East and South of Israel's lands,
 were an independent people but always greedy to exploit the fertile valleys of the Jordan. 
They spotted an opportunity, a power-vacuum, and descended on the unprotected nation. 
They even began to settle on the land.

After a time of suffering the Israelites appealed to Pharoah (the living God).
Pharoah sent an envoy to remind them that it was Pharoah who had settled them there in the first place.
He then arranges for an Egyptian (Gideon is an Egyptian name) to be appointed to sort things out.
Gideon has some difficulty in persuading the people to surrender their independence
 and return to the security of Egyptian protection(Judges 6:38=32). 

Gideon's 300 men, over whose selection the legend goes to great length, 
were probably a cohort of trained Egyptian soldiers seconded for the duration.  
The appearance of Egyptian troops on the hillside was enough to cause the invaders 
to make a wholesale retreat into the hills. 
 
 Gideon then calls up local forces to complete the rout, 
though taking disciplinary action on those who refuse the imperial yoke.
Finally he is paid off and left as effective governor of the area, 
though refusing the offer of an imperial title.
Perhaps Pharoah might not have approved.

When Gideon dies the people turn back to their own Gods,
casting off, once again, the imperial yoke.
Seemingly that only lasted 3 years
and was followed by a succession of governors
with intermittent, and briefly successful, bids for independence.
Finally stability is achieved with the advent of Saul, 
and the subsequent, seemingly, independent Davidic kingdom.

 Perhaps the key point is that references to God, or the God of Israel, in the Old Testament
generally refers to a living entity with the material power to intervene,
which is not something that the supernatural God of later years
seems to make a recognisable habit.