1861-1865. Considering the number of wars, repressive operations, foreign interference, even massacres and extermination in which the United States of America have been involved from the beginning, from the methodical liquidation of great parts of the indigenous people, to the Iraqi and Afghan quagmires, through Korea, Vietnam, Libya recently, one can reasonably ask when the hell the American people will experience a full decade without any military intervention here or there. Some people would say that anyway, thanks to the Korean and Vietnamese quagmires the share prices of Boeing, Douglas, Lockheed ... and many others have been held very high for decades!
The following archives (original anaglyphs) should remind us of the great "intramural" American slaughter called "Civil War", the first modern war ever, with implementation of children: "(They)... preferred to have young boys carry the powder to the cannon crew. Boys of 12-14 often performed this job due to their speed and small size. Speed was obvious and the small size helped to reduce them as a target from enemy sharpshooters that may be firing...". (Source)