Navy personnel using a smoke box for chemical warfare training during World War One. The smoke cloud is visible, indicating the effective use of the equipment. This photograph was taken on April 2, 1919, by a photographer with the Chemical Warfare Service.

Royalty-Free Standard Commercial licenses are granted for worldwide, non-exclusive and perpetual use, unless specifically noted otherwise. All Royalty-Free transactions are final. The Royalty-Free Standard Commercial license has no limitations and covers up to 15 users.