He saw action immediately on the outbreak of the civil war, flying with only obsolete planes like the Nieuport Ni-52 Delage, the Hawker Fury, the Loire 46 and the Dewoitine 371 where, nevertheless, he scored his first three victories.

Lacalle was very young for his duties (Tinker called him 'The Kid'), almost careless as a child when driving a car but extremely skilled when flying a plane.

As a leader, Lacalle was careful not to expose his fighters to unnecessary risks, as he knew how difficult it was to replace them, but when the duty called, he was ready to fight under any conditions.

In the Battle of Guadalajara, he ordered his planes to fly under very poor visibility conditions that surprised the Italian attackers; their columns, stuck on the roads to Madrid, were decimated.

On February 6, 1939, Lacalle left from the Vilajuiga airfield for the Francazal aerodrome near Toulouse in his last I-16 fighter, leading a great part of the planes of the Spanish Republican Air Force to France so that they would not fall into the hands of the enemy.