"...Confederate designs on a major, decisive victory against the Spanish at Havana was thrown into flux just as Johnston, who had effectively assumed command of the entire expedition (to the chagrin of Early), made the command to launch the first attacks on the Fifth of August, a Monday. His troops would force their way forward against El Morro and La Cabana, looking to secure the eastern and northern shores of Havana Harbor before settling into what would surely be a longer siege of the twin fortresses than his superiors in Richmond expected. Lee's men would attack from the west, and Early was to secure the major roads at Colon, Cienfuegos and Matanzas to make sure there would be no major movements of either Spanish or rebel troops from the east. Most importantly, Lee would enjoy Cuban irregulars tied to Salcedo as a reinforcement as he approached Havana proper, lending credence to the fact that the Confederacy was there to support a "legitimate" government that only it recognized.
The old saying goes, though, that the other side gets a vote too, and in this case that vote was with the Spanish Navy launching - with its Atlantic Squadron having sailed out of Cadiz and then resupplying in Tenerife before steaming across the Atlantic at such an aggressive pace that it threatened to deplete its coal supplies - an ambitious preemptive attack on the Confederate mainland. Having avoided a formal declaration of war in the early months of the gradual Confederate encroachment on Havana, instead supporting a "de facto" war state, the Spanish minister to Richmond informed President Breckinridge and Secretary of State Harris in the evening of Friday, the Second of August, that Spain now was in a state of war with the Confederacy until the CEF withdrew entirely from Cuba and recognition of the Salcedo Government was annulled. Breckinridge was harried by Harris into refusing that ultimatum over dinner and a Cabinet meeting the next morning, the first Saturday Cabinet meeting since the War of Independence.
That same Saturday, in a moment of opportune and unplanned timing, the Spanish Atlantic Squadron struck her three targets. Protected only by green-water harbor defense ironclads, the sloops of war struck Jacksonville, Savannah and Charleston throughout the afternoon, shelling the coastal defenses (including Fort Sumter in Charleston Harbor) and quickly sinking the ambushed ironclads that puttered out of the harbors to meet them. It was a particularly devastating attack at Savannah, where the ships sailed up the river to draw out the coastal defenders, retreated towards the mouth of the river, and then managed to sink the ironclads in a way that blocked the river temporarily to any pursuers who might sail out. In Jacksonville, the damage itself was relatively muted from the artillery bombardment - the sloops themselves avoided sailing into the mouth of the St Johns, waiting instead for the three ironclads posted there to emerge so they could be destroyed - but the Spanish Naval Marines landed instead to the south at St. Augustine, seizing the old colonial capital briefly, mockingly raising the Spanish flag over its buildings as shocked townsfolk fled after a brief skirmish, and then proceeding to destroy the Florida East Coast Railroad's (unfinished towards its objective of Biscayne Bay even at this point, of course) yards near the city and cutting telegraph wires. Though the damage was fairly minimal and repaired within a few weeks, it was an important symbolic victory for Spain. The attacks over with once the Marines retreated overnight back onto their tender to return to their vessels, the Atlantic Squadron retreated by Sunday morning and regrouped to steam south - not to Cuba, but to Key West.
The CEF was wholly unaware that the August Third Raids [1] had occurred or that the Caribbean Fleet of the Spanish Navy was headed for Havana simultaneously from their ports in Samana Bay and San Juan. And so the Battle of Havana began on August Fifth, 1872, with the push towards El Morro. Fighting began in Cojimar, where Johnston's men lost nearly two hundred dead and wounded in the first hours of fighting against merely half that for the outnumbered Spanish defenders, who pulled back as the Confederate Marines made a landing at a beachhead a quarter mile to their left flank. Johnston thought the battle was proceeding smoothly, especially as the half-mile past Cojimar was effectively empty. On the other side of Havana Harbor, Lee's men came within a mile of the water and the city, only to find the same rude surprise Johnston discovered immediately before the El Morro/Cabana complex - a vast series of trenches and earthworks, with reinforced artillery, separating the advancing infantry from their targets.
Of the coast of Havana, slowly coming closer to shore as cannonfire echoed across the water and smoke rose on the horizon, the lookouts of the Mississippi and Tennessee noticed other shapes approaching from the east, rapidly encroaching upon them, just as they pulled into shell the forts on either side [2] of the mouth of the harbor to force their way in..."
- The Cuban War
[1] All ears to anyone who has a better name for this
[2] The Castillo de San Salvador de la Punta is on the western side of the harbor's entrance, next to what would have been the entire city of Havana in the 1870s. The chains running between it and El Morro were the main harbor defense. Why do I bring this up? Oh, no reason...