The establishment of the 45th Division took place at the Aragon Front June 1937 during the planning period of the Huesca Offensive. It was initially foreseen as a provisional unit and even before it became operational General Lukács, the head of the unit grouping, died after being hit by an artillery shell and was replaced by "Emilio Kléber", the first de facto commander of the division. After the crashing failure of the new unit at the combats of the Huesca Offensive in June, the 45th Division was brought to the Madrid Front in order to take part in the Battle of Brunete under Kléber's leadership. Even though it began well at Brunete, the division did not succeed in meeting its assigned targets and ended up suffering numerous casualties. In August it went back to the Aragon Front in order to take part in the Aragon Offensive as part of the so-called Agrupación B, together with an artillery group and an engineer battalion. Sent to a front of scant activity Kléber's troops advanced without difficulty until they had to halt as they arrived at a distance of 6 km from Zaragoza. In the exposed flat terrain the troops were defenseless against the fierce attacks of the artillery and the planes of the rebels. Owing to the poor performance of the unit under his command, Kléber was replaced by Hans Kahle and the human losses were covered by new reinforcements. Wladislaw Stopzyk, a new political commissar, was assigned to the unit. In February 1938 the 45th Division fought briefly at the Extremaduran Front, where it had a measure of success in some combats. But very soon it was rushed again to the Aragon Front where it took part in the effort to halt the overwhelming Aragon Offensive of the rebels. However, the attempt proved futile and the division joined the other Republican units in the massive withdrawal that ensued. By April the rebel troops led by General Antonio Aranda reached the Mediterranean Sea dividing the Spanish Republic in two and the 45th Division would remain locked in Catalonia, becoming detached from the 129th International Brigade, which had remained in the mountainous territory south of the Ebro. Isolated from the remaining Republican territory, the 45th Division was made part of the 5th Army Corps led by Lt. Colonel Enrique Líster. During the months that followed the division managed to rearm and was reinforced by the 139th Mixed Brigade in order to be able to participate in the upcoming Battle of the Ebro. During the offensive the division held its ground against the deadly attacks of the Francoists, ending up with a very high number of casualties, especially the XIV International Brigade —part of the division— which suffered huge losses during the failed attempt to cross the Ebro River near Amposta. Following the withdrawal of the International Brigades in October 1938, the division was reorganized with Spanish leaders and recruits. Its last commander was Francisco Romero Marín, a communist war veteran. It is known that the 45th Division took part in the first hopeless Republican efforts of trying to contain the rebel onrush of the Catalonia Campaign, but it soon had to withdraw northwards to the French border. After crossing the frontier line in early February 1939 the fleeing Republican troops were disarmed and interned in concentration camps by the French authorities and the division was terminated.
