[2] In favourable weather and with proper equipment and supplies, however, military campaigns could be extended from the 'campaigning season' into winter in an attempt to catch the enemy off-guard.
For example, in the Flanders campaign, French general Jean-Charles Pichegru unexpectedly crossed the frozen Great Rivers during the harsh winter of 1794–95, and conquered the Dutch Republic.
[3] But ill-prepared winter campaigns often had disastrous consequences due to high mortality amongst the soldiers; the most notorious example of this is the French invasion of Russia by Napoleon (24 June – 14 December 1812).
The success of a military campaign is evaluated based on the degree of achievement of planned goals and objectives through combat and noncombat operations.
Such stalled campaigns, for example the western front in World War I, were formerly called "stalemates" but in the late 20th century the metaphor of a quagmire was often applied, and "frozen conflict" in the 21st.