He coined the term "fifth column".
Mola was born in Placetas, Cuba, at that time an overseas Spanish province, where his father, an army officer, was stationed. The Cuban War of Independence split his family; while his father served in the Spanish forces, his maternal uncle Leoncio Vidal was a leading revolutionary fighter. In Spain, he enrolled in the Infantry Academy of Toledo in 1907. He served in Spain's colonial war in Morocco where he received the Military Medal, and became an authority on military affairs. By 1927 he was a Brigadier-general.
Mola was made Director-General of Security in 1930, the last man to hold this post under Alfonso XIII. This was a political post and his conservative views made him unpopular with opposition liberal and socialist politicians. When the left-wing Popular Front government was elected in February 1936 Mola was made military governor of Pamplona in Navarre, which the government regarded as a backwater. But the area was a center of Carlist activity and Mola himself secretly collaborated with the movement. He worked with elements of the right-wing Spanish Military Union and by the end of April 1936 was acknowledged as its leader in north-central Spain.
Mola emerged as the chief planner among the plotters. While General José Sanjurjo, in exile in Portugal, remained the recognized leader, Mola was delegated the authority within the organization to plan operations in Spain. Known as "the Director", Mola sent secret instructions to the various military units to be involved in the uprising and worked out a detailed plan for a post-coup government. In a memorandum dated 5 June 1936, Mola envisioned a "republican dictatorship" based on the Portuguese model. The initial government would consist of a "directory" that would oversee a semi-pluralist but authoritarian state. According to Mola: "The Directory will guarantee no change in the republican regime during its administration, with no change in any worker claims that have been legally obtained" but would "create a strong and disciplined state". The 1931 constitution would be suspended and new elections would be held. Certain liberal elements, such as separation of church and state and freedom of worship, were to be maintained. Agrarian issues were to be resolved by regional commissions with the aim of developing small holdings, but allowing for collective cultivation in some circumstances.
Despite extensive planning, Mola apparently doubted the chances for the coup's success. His dim view of the capabilities of monarchist militias and the conservative Catholic party Spanish Confederation of the Autonomous Right (CEDA), as well as only limited support from the Falange, led him as late as July 9 to consider the possibility of having to flee to France if it failed.
After several delays, 18 July 1936 was chosen as the date of the coup. Francisco Franco's participation was not confirmed until early July. Although events ran ahead of schedule in the Spanish Protectorate of Morocco, Mola waited until July 19 to proclaim the revolt. When Mola's brother was captured by the Republicans in Barcelona, the government threatened his life; Mola replied: "No, he knows how to die as an officer. I can neither take back my word to my followers and probably you cannot either from yours." Said brother ended up committing suicide. Mola then ordered systematic executions in captured cities for the purpose of instilling fear. He famously declared:
... "we must extend the terror; we must impose the impression of dominion while eliminating without scruples everyone who does not think as we do (eliminando sin escrupulos a todos los que no piensen como nosotros)".
The Nationalist coup failed to gain control of either Madrid or other urban areas, though most of the army supported it. As the situation devolved into civil war, Sanjurjo was killed in an air crash on July 20. Mola then became Nationalist commander in the north, while Franco became commander in the south. With the death of Sanjurjo, Mola established a multi-member governing body for the so-called "Nationalist zone" (zona nacional) called the National Defence Junta. Based in Burgos, it was nominally headed by Miguel Cabanellas, the most senior participating general.
On September 5, a Nationalist offensive sent by General Mola under Colonel Alfonso Beorlegui took Irún and closed the French border. Mola's forces went on to secure the whole of the province of Guipúzcoa, isolating the remaining Republican provinces in the north.
A junta in Burgos proved unable to set overall strategy; thus, Franco was chosen commander-in-chief at a meeting of ranking generals on September 21. Mola continued to command the Army of the North and led an unsuccessful effort to take Madrid in October. In a radio address, he described Nationalist sympathizers in the city as a "fifth column" that supplemented his four military columns. The Republican government then proceeded to carry out the mass execution of as many as 2,000 suspected civilian and military supporters of the Nationalists. What was later known as the Paracuellos massacres crushed any potential fifth column.
Mola died on 3 June 1937, when the Airspeed Envoy twin-engined aircraft in which he was travelling crashed in bad weather while returning to Vitoria. The deaths of Sanjurjo and Mola left Franco as the pre-eminent leader of the Nationalist cause. In the assessment of historian Stanley Payne, Mola had been "the only subordinate capable of talking back to Franco." Although there have always been accusations that Franco arranged the deaths of his two rivals, so far no evidence has been produced.
In 1948, Franco, as Head of the Spanish State, posthumously granted Mola the title of Duke of Mola and Grandee of Spain. The title was immediately assumed by his son, Don Emilio Mola y Bascón.