German involvement began days after fighting broke out in July 1936. Adolf Hitler quickly sent in powerful air and armored units to assist the Nationalists. The war provided combat experience with the latest technology for the German military. However, the intervention also posed the risk of escalating into a world war for which Hitler was not ready. Therefore he limited his aid, and instead encouraged Benito Mussolini to send in large Italian units.
With the help of the British Secret Intelligence Service agents Cecil Bebb and Major Hugh Pollard, the rebels chartered a Dragon Rapide aircraft (paid for with help from Juan March, the wealthiest man in Spain at the time) to transport Franco from the Canary Islands to Spanish Morocco. The plane flew to the Canaries on 11 July, and Franco arrived in Morocco on 19 July.
On July 11, 1936, Hughes struck and killed a pedestrian named Gabriel S. Meyer with his car at the corner of 3rd Street and Lorraine in Los Angeles. After the crash, Hughes was taken to the hospital and certified as sober, but an attending doctor made a note that Hughes had been drinking. A witness to the crash told police that Hughes was driving erratically and too fast and that Meyer had been standing in the safety zone of a streetcar stop. Hughes was booked on suspicion of negligent homicide and held overnight in jail until his attorney, Neil S. McCarthy, obtained a writ of habeas corpus for his release pending a coroner's inquest. By the time of the coroner's inquiry, however, the witness had changed his story and claimed that Meyer had moved directly in front of Hughes' car. Nancy Bayly (Watts), who was in the car with Hughes at the time of the crash, corroborated this version of the story. On July 16, 1936, Hughes was held blameless by a coroner's jury at the inquest into Meyer's death. Hughes told reporters outside the inquiry, "I was driving slowly and a man stepped out of the darkness in front of me."
On 12 July 1936, Falangists in Madrid killed police officer Lieutenant José Castillo of the Guardia de Asalto (Assault Guard). Castillo was a Socialist party member who, among other activities, was giving military training to the UGT youth. Castillo had led the Assault Guards that violently suppressed the riots after the funeral of Guardia Civil lieutenant Anastasio de los Reyes. (Los Reyes had been shot by anarchists during 14 April military parade commemorating the five years of the Republic.)
On 16 July 1936, an Irish fraudster called Jerome Bannigan, alias George Andrew McMahon, produced a loaded revolver as Edward rode on horseback at Constitution Hill, near Buckingham Palace. Police spotted the gun and pounced on him; he was quickly arrested. At Bannigan's trial, he alleged that "a foreign power" had approached him to kill Edward, that he had informed MI5 of the plan, and that he was merely seeing the plan through to help MI5 catch the real culprits. The court rejected the claims and sent him to jail for a year for "intent to alarm".
Control over Spanish Morocco was all but certain. The plan was discovered in Morocco on 17 July, which prompted the conspirators to enact it immediately. Little resistance was encountered. The rebels shot 189 people. Goded and Franco immediately took control of the islands to which they were assigned.
Following 18 July 1936 pronunciamiento, Franco assumed the leadership of the 30,000 soldiers of the Spanish Army of Africa. The first days of the insurgency were marked with a serious need to secure control over the Spanish Moroccan Protectorate. On one side, Franco had to win the support of the natives and their (nominal) authorities, and, on the other, had to ensure his control over the army.
On 18 July, Casares Quiroga refused an offer of help from the CNT and Unión General de Trabajadores (UGT), leading the groups to proclaim a general strike—in effect, mobilising. They opened weapons caches, some buried since the 1934 risings, and formed militias.
The rebels failed to take any major cities with the critical exception of Seville, which provided a landing point for Franco's African troops, and the primarily conservative and Catholic areas of Old Castile and León, which fell quickly. They took Cádiz with help from the first troops from Africa. The government retained control of Málaga, Jaén, and Almería. In Madrid, the rebels were hemmed into the Cuartel de la Montaña siege, which fell with considerable bloodshed. Republican leader Casares Quiroga was replaced by José Giral, who ordered the distribution of weapons among the civilian population. This facilitated the defeat of the army insurrection in the main industrial centres, including Madrid, Barcelona, and Valencia, but it allowed anarchists to take control of Barcelona along with large swathes of Aragón and Catalonia. General Goded surrendered in Barcelona and was later condemned to death. The Republican government ended up controlling almost all the east coast and central area around Madrid, as well as most of Asturias, Cantabria and part of the Basque Country in the north. The government retained control of Málaga, Jaén, and Almería. In Madrid, the rebels were hemmed into the Cuartel de la Montaña siege, which fell with considerable bloodshed. Republican leader Casares Quiroga was replaced by José Giral, who ordered the distribution of weapons among the civilian population.
A large air and sealift of Nationalist troops in Spanish Morocco was organised to the southwest of Spain. Coup leader Sanjurjo was killed in a plane crash on 20 July, leaving an effective command split between Mola in the North and Franco in the South. This period also saw the worst actions of the so-called "Red" and "White Terrors" in Spain.
From 24 July a coordinating junta was established, based at Burgos. Nominally led by Cabanellas, as the most senior general, it initially included Mola, three other generals, and two colonels; Franco was later added in early August.
In July 1936, British officials convinced Blum (the prime minister) not to send arms to the Republicans and, on 27 July, the French government declared that it would not send military aid, technology or forces to assist the Republican forces. However, Blum made clear that France reserved the right to provide aid should it wish to the Republic: "We could have delivered arms to the Spanish Government [Republicans], a legitimate government... We have not done so, in order not to give an excuse to those who would be tempted to send arms to the rebels [Nationalists]."