The long absence of a family member changes the entire family environment. The deployment of a service member has a strong impact on family relationships. This longitudinal study aims to analyze motivations, emotions, and changes experienced by soldiers and their spouses during a mission: anxiety, positive and negative emotions, social support, family and life satisfaction. Soldiers and spouses answered questionnaires during the three main phases of the mission (Wave [W] 1: predeployment, W2: deployment, W3: postdeployment). Soldiers also completed a questionnaire 6 months after they returned home (W4: follow-up). The sample (N = 313) comprised 255 male soldiers of the Portuguese Army (27–51 years old) and 58 female spouses (19–52 years old). A total of 123 participants had children at the time of the mission. The main reported reasons to go on a mission were personal fulfilment, career goals, and earning extra money. Higher levels of predeployment and postdeployment anxiety were observed among soldiers and their spouses. Service members exhibited more difficulties when deployed, whereas for their spouses, predeployment and deployment were more stressful periods. Soldiers who responded to the 6-month follow-up reported a lower capacity for adaptation and reintegration than they had at postdeployment. This study contributes to the construction of programs and/or actions that promote the achievement of “competences for a positive adaptation” and higher personal/family resilience, and it helps understand the reintegration of the soldier into the family environment to recover the family dynamics that existed before the mission.