French-captured German trench at the Somme; railway gun heads ammunition train

Quick shot title card: "At last the great Allied offensive on the Somme has begun and ammunition cars and huge cannons are being rushed to the points of attack to sweep the German lines" / cannon mounted on carriage with soldiers riding on it heads train of ammunition cars moving down track / German soldiers running out of trench surrendering with arms up, barricades in field / soldiers running / looking down at soldiers in German trench captured by French; wounded carried along with seized machine gun, some soldiers looking into camera / soldiers by camouflaged big gun mounted on railcar carriage in field; barrel being lowered; smoke wafts into shot / looking down on French railway gun with barrel being lowered, soldiers behind and to side / Note: exact month/day not known; film has nitrate deterioration