Snuff is actually a smokeless tobacco. It is made from ground or pulverized tobacco leaves. The name comes from the consumption method in which you inhale it, or snuff it into your nose, making it deliver a low dose of nicotine followed by a scent of its own.
Russian troops were mobilized against Austria-Hungary because Russia believed that Germany was hiding under the guise of the assassination of Austrian Archduke Franz Ferdinand to launch a war and protect their powers in the Balkans.