Fence and Retaining Wall

I have been asked to help build a hardwood fence about 15m long along the top of a hardwood retaining wall.

My concern is how to best secure the posts. Should I bolt the posts to the rails inside the retaining wall and then backfill the wall with gravel and soil. Or do I backfill and then dig post holes ?

The issues I see are: 1. If the posts are bolted to the rails, wind acting on the fence could weaken the retaining wall (1m high), 2. Digging post holes into newly backfilled soil is not a firm enough footing.

Your thoughts please.
thanks
Derek

I'd just dig post holes....just make sure the retaining wall back fill is reasonably well compacted first.

On the other hand, bolting to the retaining wall is fine too......Brisbane isn't that windy and the ground pressure of a well made retaining wall is considerable....

But I'd stick with the former because it is simpler....