¿Qué estaba pasando? Imperfect continuous, preterite interruptions

The Spanish Civil War happened between 1936 and 1939. Franco became a dictator and ruled Spain until his death in 1975. The imperfect continuous is for ongoing past actions; form it with the imperfect of ‘estar’ and the present participle. In the imperfect continuous, reflexive pronouns can go before the 1st verb or be attached after the present participle. The preterite tense is used to talk about events completed in the past. When 'cuando' indicates an interruption to ongoing past actions, the preterite tense is generally used afterwards.