Final answer:
The Russians were driving south against the Turks due to expansionist policies, strategic interests, and the protection of fellow Slavs and Orthodox Christians.
Step-by-step explanation:
The Russian forces were driving south against the Turks for several reasons. One reason was the expansionist policy of Russia, which aimed to gain control over Ottoman territory. Another reason was the strategic importance of the Black Sea region, which was a major trade route and provided access to warm-water ports. The Russians also sought to protect the interests of their fellow Slavs and Orthodox Christians living under Ottoman rule.