History of the 151st field artillery, Rainbow Division, by Louis L. Collins, lieutenant governor of Minnesota. Edited by Wayne E. Stevens, PH. D. Pub. by the Minnesota War records commission.

54 HISTORY OF THE 151ST FIELD ARTILLERY

On Saturday, May 25, observers reported increased activity
behind the enemy lines. O'n the same day German planes, flying in
formation, made repeated trips over the American lines. Warning
was issued for the division to be on the alert for a gas attack
and on the next day a severe shelling of roads and battery positions strengthened the conviction that the Germans were about to
attack.19 Moreover, a German deserter, an Alsatian by birth, who
came into the lines on May 26, also predicted a gas attack. It came
at ten o'clock on Monday night, May 27, after a day of severe shelling. At that hour a gas attack was launched by a combination of
projectors and shell fire, the infantry in the front lines and in the
villages back of the lines being subjected to a projector attack and
the artillery positions being shelled heavily with high explosives
and gas. In Village Negre two officers and about twenty-eight men
of the 168th (3rd Iowa) Infantry were killed, as were also two
Y.M.C.A. men who had been working in Negre. Three hundred
men were wounded, about forty of whom later died. The 1st Battalion of the 151st had opened fire coincidentally with the German
attack; this was kept up until morning, the men at the guns wearing gas masks for hours. Fourteen men were overcome by gas
and taken to the hospitals.
Two guns of Battery C had been moved to a position near
the French battalion of chasseurs, west of Village Negre, to meet
the expected attack; one gun was left in the old position; the
fourth had been disabled. Lieutenant Leopold Arnaud went to
the old position under heavy fire and called for volunteers to stay
with the one gun. Having sent the other men back to deep dugouts, he remained at the gun all night, the six volunteers firing the
specified barrages. Before morning all of the men were overcome
by gas and the lieutenant himself, aided by a rocket guard, fired
the gun.20
'9Five casualties on that day included Private Hans Thorstad, severely
wounded.
20Casualties for the day numbered twenty-nine, including Corporals Ira
M. Curtiss, Russell S. Swain, Privates Nicholas Becker, Harry C. Martz,
George H. Morgan, Walter Muff, Walter G. Nelson, LeRoy Paul, and Warren
A. Tangen, all severely wounded or gassed.