sure, but in SanGuoZhi, it said the ZGL sent Ma Su AHEAD,

as Ma Su was the Vanguard: 亮使马谡督诸军在前，与邰战于街亭. But if what you are saying is true. Ma Su was protecting the supply depot at the flank? If so, then what I had said still make sense. If ZGL do come into Jie Ting from the North to battle Zhang He. Zhang He could have used Jie Ting to stall him, while getting reinforcement to ZGL's back and could attack ZGL's flank and even into Shu to break Shu's morale. But if SanGuoZhi was true, then ZGL couldn't achieve his goal since Ma Su screwed up ahead of his arrival and now Jie Ting could be used against his advance. But I still need to see a map of his advance to determine geographical positioning. Please send me the link and I hope the map is detailed in geography.