Wine is a way of life literally rooted in the soil. It is also capital and labour intensive and reliant on a complex distribution network, which make it highly vulnerable during time of war.
The most visible effect of war is the destruction of vineyards. Just as it was customary for warring ancient Greeks to cut down or burn the vines of their enemies, so the barbarian invaders of Roman Europe signalled victory in the same way.
Planting on newly captured territory likewise symbolized success. When the Christians drove the Moors from medieval spain, they planted vines behind them, as did the Crusaders who briefly held parts of the Holy Land. It is difficult to imagine a clearer expression of a battle won and determination to stay than the planting of such a long-term crop as vines.