So what was the motive behind the S1 assassination attempt on Smith?

The closest thing we get to an explanation is that senior officers have often killed other officers... but that doesn't explain anything. So:

1. Heydrich tries to assassinate Smith, and fails
2. Heydrich, instead of trying again, tries to recruit Smith instead
3. If Smith would refuse the offer, Heydrich would again decide to kill him

Why try to assassinate Smith first, then? Why not try and recruit him first?
Or if "Smith must die" should be number one on the list, why not try again when the attempt fails? Pretty odd timing to decide to recruit him instead.

But why did Heydrich want Smith dead in the first place?