It is the stated policy of the Ukrainian government to retake all of the territory that Russia has seized since 2014, including Crimea. To achieve this goal through military action, the Ukrainian military must accomplish one of the most daunting of military tasks: It must break through dense, well-prepared defensive positions, find some running room, and then either move quickly toward an important geographic objective such as the Sea of Azov, hoping to unravel the remains of the defending Russian army along the way, or quickly attempt to encircle a portion of Russia’s sizable forces in hopes of annihilating them.
To fail at this kind of campaign will mean that Ukraine is likely destined for a long war of attrition—an inauspicious one, pitting it against a much more populous country. Ukraine naturally wishes to avoid the attritional war by succeeding at its breakthrough campaign. But military history suggests the challenges here are also more daunting than have been commonly understood—at least among the public in the West.