Infernum

Nigra scuta, tincta corpora; atras ad proelia noctes legunt ipsaque formidine atque umbra feralis exercitus terrorem inferunt,
tincta corpora; atras ad proelia noctes
nullo hostium sustinente novum ac velut infernum

In english
They wear black shields, their bodies are painted black, they choose dark nights for engaging in battle; and by the very awe and ghastly hue of their army, strike the enemy with dread, as none can bear this their aspect so surprising and as it were quite infernal.
their bodies are painted black, they choose dark nights for engaging in battle;
as none can bear this their aspect so surprising and as it were quite infernal.
[ Taken from Tacitus Germania ]