History has not been kind to fortresses. WWII saw the Germans march around the Maginot Line and in the far east, the British at least still remember “Fortress Singapore”, whose massive armament was supposed to stop the Japs cold. As the Japanese invasion fleet grew nearer the Brits affectionately patted their huge guns, all pointed seaward, and actually complained that the Fortress was so strong that it might scare the Japaneses away and thus deprive the English empire the chance to eliminate them permanently.
Which was all very reassuring until those nasty Asians chose to attack from the rear, behind those guns, and on bicycles yet (!). The island fell in just a couple of weeks.
It’s possible that using Germany’s money to fortify Spain and Portugal will save the Eurozone. It’s also possible that there’s a back door left ajar that will bring the euro house of cards tumbling down. Stay tuned.