The New Republic did have a Fleet, but a large chunk of their fleet were stationed at Hosnian Prime. I’m sure some New Republic forces exist throughout the galaxy but they’re all spread thin. So by destroying Hosnian Prime, it would be like if the attack at Pearl Harbor had destroyed the carriers and oil facilities like the Japanese had hoped for. It would have been a major setback for the United States.
At this time, I think the New Republic relied on the defense forces of their member worlds to be called to action in a situation where a large defense force was necessary. I believe the NR’s primary defense fleet was large enough to handle any large scale conflicts itself, but I imagine in this time they only dealt with intervening skirmishes involving their members, or fighting off pirates/criminals.
The New Republic demilitarizing to me wasn’t about having no military, but downsizing their military to pre-Clone War levels. Basically to the scale that the Republic Navy was at probably for most of its history. Many people didn’t want a large national military so the central government wouldn’t have too much power over its member worlds, leading to an abuse of power that led to the Empire in the first place.
I also like to think that between ROTJ and TFA, the New Republic did deal with some Imperial holdouts, but their threat to the Republic was small enough for their Fleet, and units like Rogue/Wraith Squadron from the EU, to take care of. While not really necessary, this would also help explain why they never consider an Imperial resurgence a major threat.
But we do know that First Order sympathizers within the Senate did help downplay the threat of the First Order enough to make the majority of the Republic feel like a large-scale intervention wouldn’t be necessary. And it did seem the First Order kept hidden enough to help with that narrative.
But once the First Order destroyed the Defense Fleet and the Senate in one move, it was basically cutting off the head of the Republic. The member worlds no longer had any leadership or unity. Maybe under some common leadership they could’ve held back the First Order, but without it they’re all probably bunkering down in an attempt to defend their own worlds. It’s a very precise divide and conquer-like strategy, a strategy which smaller armies can use to defeat forces larger than itself.
So my guess for the First Order’s strategy (which they’ve had 30 years to perfect) could be to occupy planets at important hyperspace junctures, thereby having control of trade and the galactic economy within a month or two.
Which in my mind is why Leia’s survival in TLJ was so important. She might be the last figure that can truly unite what is left of any resistance in the galaxy together, which we will hopefully see in Episode IX.
I like your explanation RogueLeader, but I’m left with one final question. Where the hell does the FO get all its money from? Because doing business with them is a surefire way to get Canto Bight levels of wealth. Imperial credits shouldn’t be an accepted form of currency in the NR. Do the Unknown Regions have an abundance of precious minerals that are highly coveted throughout the Galaxy?