If one looks purely at the strategic position and numbers of troops under arms in early 1939, the Republic's fate appeared far from sealed.
True, the Ebro offensive had failed, but the losses for each side were roughly equal. Economic conditions were deteriorating in the Republic, but the burden of attack remained on Franco and the Nationalists. Whether they chose to strike at Madrid or Barcelona, the fighting was sure to be slow and costly.
The subsequent Republican collapse took everyone by surprise. There was tough fighting at first, but then the Republicans fell back in total disorder. The Nationalists advanced as fast as they could march.
Despite having multiple prepared defensive lines in place, Barcelona was yielded without a fight.
This once again demonstrates how important - and fragile - morale can be.
My analysis of the war in Long Live Death puts great emphasis on fighting spirit and the factors that sustain it, but the importance of morale is featured to one degree or another in all of my books. People rarely fight to the death - particularly if they know it won't make a difference in the ultimate outcome.
We tend to think of battle fronts moving gradually and incrementally, but just as often they slip only a little before coming completely apart. Once that happens, it's very hard to turn things around.
The blow to prestige can also be catastrophic. Even unengaged troops can be affected by a rout.
That's also what happened in Spain. Even though the forces on the Madrid front were fully intact, watching their comrades in Catalonia flee to France destroyed their fighting spirit as well. The Republic lost the will to fight and Franco's victory was complete.