Then He Commanded the Disciples to Go and Buy 200 Denari Worth of Bread and Give It to Them to Eat

Jesus takes compassion on the crowd as they are like sheep without a shepherd. The wilderness is the natural place to reform Israel, it's reminiscent of God's original formation of his people in the wilderness after he led them up out of Egypt. In the second half of Mark chapter 6 the apostles returned from their mission with news of their success. However even though they tried to get away for some solitude they are immediately recognized and the crowd follows after them. Like Jesus they need time to refresh themselves and regain their strength.