Group of Eastern Region Armies

Eastern Region Army Group Grupo de Ejércitos de la Región Oriental (GERO)
Military flag of the Popular Army
Active	2 June 1938 – 9 February 1939
Country	Spain
Branch	Spanish Republican Army
Type	Army group
Role	Home Defence
Garrison/HQ	Igualada
Engagements	Spanish Civil War Battle of the Ebro Battle of the Segre Catalonia Offensive
Commanders
Notable commanders	Juan Hernández Saravia Enrique Jurado Barrio

The Eastern Region Army Group, Spanish: Grupo de Ejércitos de la Región Oriental (GERO), was a military formation of the Spanish Republican Army during the last phase of the Spanish Civil War. It was established in June 1938 as a response to the splitting in two of the territory under the sovereignty of the Spanish Republic after the Central Region Army Group (GERC), under the command of General Miaja, had been set up in the central-southern region of Spain.

This army group of the Spanish Republican military lasted until the Fall of Catalonia on 9 February 1939.

Catalonia had become an isolated enclave following the rebel Aragon Offensive in the spring of 1938. Since the loyalist armies of the former Aragon Front were in a state of disarray after the Republican debacle, the President of the Spanish government Juan Negrín requested the Chief of Staff commander of the Republican Army, Vicente Rojo, to reorganize the Republican forces.

Owing to the loyalist territory having been split in two by the rebels, General Rojo saw the need of establishing two army groups in order to coordinate the specific defence requirements of each zone. Thus after the establishment of the GERO, a new Eastern Army was organized in the Catalan territory, in charge of the defensive line of the Segre River. Meanwhile, in the southern sector the Ebro Army was established, which would have as its goal to eventually reunite the northeastern Republican area with the larger zone further to the southwest. The commander of both armies was a prestigious military figure, General Juan Hernández Saravia, who had been the former commander of the Southern and the Levantine Army.