The Army of Rogues
Longstreet was stunned at what the White House had done. As far as he was concerned, their removal of President Morgan was blatantly illegal and unconstitutional. Longstreet was no fan of Morgan at all (he openly admitted he had voted for the CSIP candidate), but Longstreet still believed that he was the legitimately elected President. Worst of all, the palace coup against President Morgan by Vice President Miles seemed to have the worst reasoning: making peace in a war that as far as Longstreet could tell, he was easily winning. Worst of all, the Confederate Army in Cuba, was part of the peace agreement, was ordered to disarm the Cuban rebels before retreating, which would mean betraying their close allies.
The Confederates knew exactly what this felt like. In the War of Southern Independence, as a general in the Army of Northern Virginia, Longstreet had keenly known that the Union was definitely winning and would have won if not for McClellan's assassination (by abolitionist radicals no less!) and the ascendance of President Pendleton. Similarly, the Confederacy was ultimately winning in Cuba! Yes, massive Spanish reinforcements had forced them into a guerrilla fight, but it was clearly a losing fight Spain had picked. Spanish superiority in artillery and on sea meant little when Confederate-Cuban forces could launch hit and run attacks, using both their expertise in melee combat and superior small arms to devastate small Spanish garrisons, before disappearing again into the countryside. Spanish losses in battle were horrible, not to mention disease and widespread desertion.
Indeed, many feared that the Spanish escalation of the war by attacking New Orleans would trigger an intervention by Great Britain or the United States. However, the Spanish went ahead anyways, figuring that the only way to defeat the Cuban rebels was to defeat the Confederacy - and the only way to defeat the Confederate was to strike them directly. Such strategic planning, supported by Prime Minister Juan Prim was more or less correct. However, the Spanish had not counted on the Confederate Army in Cuba simply refusing to disarm even after the civilian government in Montgomery threw in the towel. Longstreet wasn't alone - almost all of his subordinates agreed. The government in Montgomery was not legitimate and the war was not yet over - they were supposed to win it!
Interestingly, while the Confederate Army in Cuba remained loyal to President Morgan, they didn't actually follow his precepts. Morgan had sought to annex Cuba in order to preserve it as a slave state. However, after a year of fighting and struggling besides Cuban officers and soldiers, most Confederate officers became deeply skeptical of the notion of annexing Cuba as part of a Golden Circle, sympathizing instead with the notion of Cuban independence (though Cuba would presumably be very close to the Confederate States).
In shock that the peace agreement had been "broken", the Spanish continued their next planned assault, a bombardment and seizure of Fort Sumter (rebuilt from rubble as a symbolic victory and then blasted into rubble again) and a Marine assault on Charleston. With most of the Confederate Army tied up in North Carolina being defeated by Stonewall's crusaders, the second largest city in the Confederacy also fell, with reports of a Spanish assault on the third largest city, Mobile, quick to arrive. New Orleans and Charleston were also some of the wealthiest cities in the Confederacy, and stories of frenzied Spanish looting sparked fear, but also anger in the Confederacy. The Spanish encouraged such looting as they figured that further damaging the Confederacy would finally get the Confederate Army out of Cuba.
With reports that the Spanish Army was approaching Mobile, elements of the Confederate Army were called up, marching through the capital of Montgomery where they would presumably march down south to defend Mobile from the expected Spanish assault. However, one man had another idea. The head of the army sent to defend Mobile was one of the Confederate Army's best engineers, General William Mahone, who famously helped dig many of the trench networks that bought the Confederacy the months it would need to grind the Union into defeat. Corresponding with various factions of the Confederate Army, Mahone became convinced that something dramatic would have to happen if the Confederacy was to win the war.
His army, instead of simply stopping by for Montgomery for resupply, surrounded the Capitol House and White House. For the second time in a decade, rifles were pointed at the Confederate seat of government. After a brief firefight (seven were wounded, but none of them died), Mahone arrested the Confederate cabinet, claiming that they had illegally deposed President Morgan. Amusingly, President Morgan had gone to meet his closest supporters in the United Provinces of Central America, so Mahone declared that Morgan was also unable to serve and that he would serve as Acting President as the "Chairman of the National Salvation Committee of the Confederate States of America." Although Mahone thought Jackson was a nut, he nevertheless sent Jackson a telegraph, recognizing him as Governor of the Christian Commonwealth of North Carolina, ordering him to march his army south into South Carolina to evict the Spanish out of Charleston.
Most of the state governments didn't know how to respond. The states most opposed were South Carolina, Mississippi, Louisiana, and Alabama. However, with Charleston and New Orleans under occupation, those governments were willing to give Mahone a shot to at least beat the Spanish. The Alabama state government was also seized in Montgomery, which dealt with that problem. Finally, Mississippi resented Mahone, but with Spanish ships sailing down and up the Mississippi, raiding commerce, they at least kept their tongue silent. Louisiana was so outraged by the Sack of New Orleans, that Governor P.G.T. Bureaugard became the first Governor from the Constitutional Democratic Party to openly endorse Mahone's National Salvation Committee. As a result, the floodgates soon opened, with Tennessee, Texas, Florida (terrified of the Spanish), Arkansas, and Mahone's native Virginia also endorsing. The only state to condemn Mahone's assumption of "Emergency War Powers" was Georgia.
Mahone promised to crush the Spanish, both at home and in Cuba. However, he knew this was a tall order. He knew that the Confederacy did not have the naval power to seek the overwhelming victory he needed. The Spanish weren't trying to occupy the entire Confederacy, they were just looting coastal ports. Naval power would be needed to stop them. As a result, he sent a fateful telegram abroad, asking for help. He was rebuffed by London, Paris, Berlin, Rome, and even Lisbon (he wasn't even sure why he asked the Portuguese for help). None of them wanted to spark what they feared could explode into a broad European war. Interestingly, only one telegram was returned with anything but a total denial: a reply from President Cassius Clay of the United States of America.