Garden wall leaning over due to rain: please advise on drainage

[funnyperson]

I would appreciate advice on how to maximise drainage of our garden wall so that it doesnt lean over due to the weight of wet soil. It is built on a hill and has cracks in so we are having to take it down and rebuild it anyway, but I dont want the problem to recur.

clay pipes poking through it at intervals of one metre or less up, down and sideways

back-filled with large clean stones and rubble for a foot on the hill side, with landscape membrane protecting the backfill from mud washing in from the back or above and clogging the drainage.

thank you