. . "86 battalions," . . . . . . . . . . "580 guns" . . . "1,250 killed" . . "initial success" . . . . . "Russian victory" . . "Battle of Gumbinnen" . "6,414 wounded" . . . . . . "Gumbinnen" . . "Details" . . . "Russian victory" . . . . "Total:" . . "1914-08-20" . . "105 battalions," . . "204 machine guns," . . "6,943 captured" . . "Battle of Gumbinnen" . . "14,607" . "55 squadrons," . . . . . . . . "252 machine guns," . . "408 guns" . "130 squadrons," . "Russian successes" .