The War in the North was a series of battles in the Spanish Civil War and marked the first full-scale engagement between Soviet-Italian and Nationalist forces in Spain. This theater of war included several battles over a wide range of Spain's provinces that culminated in the Siege of Valladolid, where more than 150,000 Republican, Soviet, and Italian troops besieged the city that housed less than 50,000 Nationalist soldiers. Valladolid also suffered massive damage from the aerial and mortar bombardment from both forces, with the Republican forces immediately heading south after the battles to support the Southern Spain theater of the war.
The overwhelming amount of soldiers, added by the fact that the Soviet Union and Italy gave immense material and logistical support easily tipped the balance into the Republicans' favor. The campaign was a significant raise to the already-high Republican morale as it secured Madrid from a rear attack, while drastically reducing hope for the Nationalists' goals.
Start of Hostilities
In April 1, thousands of Nationalists under Mola revolted all over Northern Spain, seizing control of multiple cities including Valladolid and Pamplona. The Republican Army was distracted at first due to the scale of events happening, and only managed to restore communications a few hours after the uprising. By then the Nationalists had surrounded the Republicans and thought they had them running, but in reality, the Republicans were merely consolidating their forces and started to retreat to the north, encountering sporadic Nationalist forces in the first few weeks.
The Battle of the North
The Battle of the North was a series of battles taking place immediately after the Nationalist revolution in northern Spain. The Republicans choose a strategy of abandoning large swaths of land and concentrating their forces into large groups in order to have the maximum amount of firepower and troops should they decide to counterattack. This also benefited the cities and their citizens at the start because this drastically reduced the amount of urban fighting in the beginning of the war and saved countless lives. Only a few thousand military casualties were lost in this part of the war, and the Nationalist rebels managed to capture three dozen aircraft which they hoped would turn the tide in their favor.
Republican intelligence estimated the Nationalist forces who surrounded them to be numbered around 100,000 men. This gave the Republicans a slight numerical advantage but that advantage meant nothing as they were cut off from supplies, rations and weapons with the rest of Spain. The entrapped Republicans had to resort to air raids in the hopes of destroying Nationalist weapons and equipment crucial to their war effort as only Portugal was willing to openly supply the Nationalists, but did so minimally due to an open Soviet threat of invasion against the weak state.
By mid-May, the Republican airstrikes had killed around destroyed around 25% of Nationalist equipment, armoured vehicles, plus valuable fuel and weapons that reduced the Nationalists' capabilities to continue a full-fledged war in the north, and by May 20, the Republicans saw the perfect opportunities for a counterattack: 65,000 troops had engaged the rebels in Vergara and the remaining soldiers attacked the surrounding areas and aimed to take control of Leon and Burgos. Despite being outnumbered in every battle excluding Vergara, the air superiority of the Republicans more than made up for the number disadvantage, and by the end of the month, Leon, Burgos, San Sebstien were reclaimed by the Republicans.
Soviet and Italian Intervention
By the end of May, the Republicans had manage to reclaim all of coastal Spain in the North, and were gearing up to siege the city of Pamplona, a rebel stronghold home to 35,000 defenders. The city itself was well-barricaded and well-protected with entrenchments built in and out of the city. The aircraft the Republicans used in the initial offensive had been reduced to half of its number, with all of the ones remaining used to bombard rebel armies in Castile and La Rioja. There was simply no way to take the city without sustaining heavy casualties, but the arrival of 25,000 Soviet and Italian volunteers, along with a hundred aircraft and dozens of tanks quickly changed that. In June 18, the Republican coalition of forces laid siege to the city. The arrival of re-inforcements with advanced weaponry and additional aircraft was effective at toppling Pamplona, but the victory was not a decisive one as 20,000 Nationalist soldiers managed to slip away into Castile and eventually Valladolid, but it was a victory nonetheless. The Soviet and Italian intervention marked the beginning of the end for the Spanish Civil War in the North
The previous battles were all a stalling action as the Republicans' Coalition saw the province of Castile and Leon to be entirely full of entrenchments, fortifications, and traps, alongside the remaining 70,000 Nationalist defenders. The Nationalists were also able to steal 50 Republican Aircraft in the midst of all the fighting and used them to strike down Republic bombers. The Coalition generals then decided to slowly defeat the rebels in a war of attrition to starve them of food and supplies, where the Republican troops invaded from the North, and the Soviet-Italian troops invaded from the east, and to allow the heavy vehicles time to traverse the urban and rural terrain of the area. By July, 90% of Castile and Leon was under Republican hands and only 35,000 Nationalists remained and all of them huddled in the rebel fortress of Valladolid, the most heavily-protected city of the rebels. By August 20, Valladolid itself was under siege from the air and from the ground.
Fall of Valladolid
On August 20, the entire city was surrounded by 98,000 Soviet, Italian, and Republican troops. Adalberto Bosque himself came to the battlefield to try negotiate a truce with the rebels, but all his attempts were in vain as not one of the five negotiators he sent returned alive. He then ordered a 2-day aerial and artillery bombardment against the city while the troops regrouped and resupplied. The smoke emerging from the city was said to be seen from Madrid itself, but this was disproven. On the dawn of the 22nd, the Republican Coalition invaded the city, battled by the remaining soldiers and a few hundred sympathizers. Some Nationalists even went into battle with nothing more than swords, knives, or even their bare fists as weapons and bullets ran low. The Soviet general advised to send in tanks and armoured vehicles, but Valladolid's tight roads discouraged this. By the end of the day, Valladolid laid in smoking ruins as you could see the northern and southern ends of the city if you stood in the middle of it
By the end of the theater of war, 111,000 soldiers, more than half of those Nationalists, died in the fighting with 45,000 civilians dead as well. Dozens of Spanish cities, most notably Valladolid, laid in ruins due to the intense fighting that occurred. The area would not successfully recover until a decade after the Civil War. The conclusion of this theater prompted the Coalition soldiers to quickly head south in order to support the Republicans in Andalusia and Toledo.