You should march against an enemy who is not provided with contented and healthy combatants. When everything's is favourable, the enemy may be beaten. After that however, the victor should retire.
पर्युपासनकाले तु विपरीतं विधीयते। आमर्दकाले राजेन्द्र व्यपसर्पेत् ततः परम्॥