During a combat showdown, do "when I defend" triggers go on the stack first or do the "when I attack" triggers go first?

During a combat showdown, "when I attack" triggers are added to the chain first, followed by the "when I defend" triggers.

According to Rule 442.1.b.1 and Rule 342.1.a, the sequence for placing triggered abilities on the initial chain is as follows:

1. Attacking player (who has Focus) adds their triggers to the chain first.
2. Non-defender players (in turn order) add their triggers.
3. Defending player adds their triggers to the chain last.

Because the chain resolves in a Last-In, First-Out (LIFO) manner, the "when I defend" triggers (which were added last) will resolve first, and the "when I attack" triggers (which were added first) will resolve last.