Question of armed Citizens as a deterrent-

Questions: “do mass numbers of citizens armed act as a deterrent to invasion or are they effective against their government turned tyrannical.“

1st the question of “a deterrent to invasion”.

There are some 80,000,000 to 150,000,000 (est.) private gun owners with over 300,000,000  guns, billions of bullets in the US, not to mention all the military grade weaponry hidden just in case or as one might say here in N. Colorado “Cache la Poudre”.  Also, all the creative household made explosive devises from Molotov cocktails to pipe bombs to chlorine bombs to mustard gas to propane bombs, and other IEDs just to mention a few.  There is no way this, even on its own, can be seen as insignificant.  Couple that with the part time US Army “The National Guard” and the US Regular Army, it has to give pause to invasion.  Japanese Admiral Yamamoto-    "You cannot invade the mainland United States. There would be a rifle behind each blade of grass."  While not the main reason to avoid invasion, it was a consideration.  The French Resistance (nonmilitary civilians) did a good job of disruption and fighting back the Nazis. The puny Afghan rebels against the Mighty Soviet Machine is an example of effective rabble fighting back.  It was part of the old Soviets concerns about a non-or limited-nuclear invasion of the US.  The US in general has different thoughts on defense than “Modern Civilized” Europe and many of the 80,000,000 to 150,000,000 would raise their weapons against foreign invaders to avoid being enslaved or led like sheep to slaughter.  Just think, that’s more than the entire population of England or France or Germany.   And yes I would hope there were US military entities remaining to help carry on the fight.

2^nd  “the protection against the government if turned tyrannical”.  Keep in mind this is all theory, as it has not happened in recent times on the scale it would be. It also would depend on a multitude of political actions and social events. 

I hear some with sentiments much akin to those of politicians, military officers, reporters, upper class folks at the start of the Civil War> It will be over in a couple weeks.  A total underestimate of their opponent.  All the military people I have spoken with, over the 40-50 years of discussing gun control and the 2nd Amendment, agree that a force even if unorganized like much of the armed US citizens is something to be reckoned with and can not be dismissed.  These have been family, friends, acquaintances and strangers (retired and serving) – ranging from privates to Sgt to Captains to Majors to Colonels.  They would disagree with the espoused theory armed civilian resistance would be nothing to the modern army.  They believe if push came to shove it would be very messy on both sides and unpredictable. 

People think of hunting weapons as though they are one step above a toy when compared to military weapons.  Check the specs of the 5.56 NATO Round (most common military round used) compared to the 30-06 or .300 or .338, 7mm mag or .700 or .905 factory loads (not to mention hot loaded).  It’s slower, effective range is about 1/3 or less, ft/lbs about ¼ (kill power) or less, and worse.  Check the destructive power of a short barreled or sawed off no choke shotgun using double aught or triple aught or even 4 Buck 3”  mag shells reloaded with out restricting shell cup.  With my Remington 30-06 I have an effectively range of 1000 yds, personally keep my kill range to 400 yds or under.  Mountain goat hunting in the Rockies is often mountain ridge to mountain ridge using a gun like the Weatherby 300. 

Then as seen in many military operations, the resistance begins to amass captured weapons from fallen military and failed security.  (above also applies to invasion argument) 

All those military folks who had or are seeing action now will soon most all be civilians with their knowledge of war, along with Iraq war vets + Afghan vets + Vietnam vets.  Most opposed to tyranny will bring their war experience to the fray.

On top of all this add in a splintered military to muck the waters.

**I AM NOT MILITIA OR CONSPIRACY THEORY PERSON.  I look for what was and what might be (good and bad).  I support the reasoning for the 2^nd amendment, to be prepared against foreign invasion and government turned monster.**