An analysis from the Finnish East and West Cohort of the Seven Countries Study tested the hypothesis that front line service during modern warfare is associated with depression later in life. World War Two-era Finnish combat veterans were compared to Finnish veterans who were non-combatants. Both groups were followed from 1959 to 1984. Dependent variables were the Zung depression scale and other measures of psychosocial adaptation and mental health. Analysis of variance of Zung scores by combat exposure was close to statistical significance (p = 0.0501). Even if statistical significance had been reached, it is felt that the absolute magnitude of the differences between the populations appear quite trivial. A significant association was found for those who had participated in over nine battles and when grouping depression, sleeplessness, paranoia, hallucinations, schizophrenia, and other mental illness into the general category of any mental illness (O.R. = 4.414; 95% C.I. = 1.113, 17.503). This seems to support the residual stress hypothesis pertaining to modern combat exposure.