Does a monk with Extra Attack trigger Martial Arts if only one attack is unarmed?

Question

So, I've created a "sumo" monk who has the Grappler feat, and is now level 5 and has the Extra Attack class feature. Since I'd like to use one of these attacks to grapple the target, can I use my other attack to punch the grappled target, then use Martial Arts to punch him again?

Grappling:

When you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack, a grapple. If you're able to make multiple attacks with the Attack action, this attack replaces one of them.

Martial Arts:

When you use the Attack action with an unarmed strike or a monk weapon on your turn, you can make one unarmed strike as a bonus action.

Specifically, the wording of Martial Arts doesn't really take Extra Attack into account, since you could make one of those attacks with a monk weapon and or unarmed strike, then draw a longsword and make the other attack with that (or in my case, grapple). I know that Martial Arts does also say "while you are unarmed or wielding only monk weapons", which the longsword example would contradict, but my grapple example doesn't, since I'm still not wielding any weapons or wearing armour/shield.

So my question is Is Martial Arts triggered if only one of the two attacks is an unarmed strike or monk weapon attack (with the other being a grapple), or do both of them have to be unarmed strikes/monk weapon attacks?

Answer 1

Yes, yes you can!

The Monk Martial Arts requirement states (emphasis mine):

When you use the Attack action with an unarmed strike or a monk weapon on your turn, you can make one unarmed strike as a bonus action.

And Extra Attack stipulates:

Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn.

Nothing in the language of either requires ALL attacks to be made with unarmed strikes. It only requires that you use the Attack action (you did) with an unarmed strike (you did with one of your attacks) in order to be able to use a bonus action unarmed strike.

Is grapple an unarmed strike?

Grappling would not be considered an unarmed as it is not listed under the Unarmed Strikes but in it's own section that states (emphasis mine):

you can use the Attack action to make a special melee attack

Grappling (while still unarmed) is not part of the options for Unarmed Strikes as it is distinctly a Special Melee Attack.

This is also confirmed by Jeremy Crawford:

The shove and grapple options don't involve an attack with a weapon or an unarmed strike, so no

As long as you use your Extra Attack for an unarmed strike, you will be able to use your Martial Arts for a Bonus Action Unarmed Strike.

Answer 2

Yes.

As long as one of your attacks during your Attack Action is an unarmed strike, you may use Martial Arts to make one extra unarmed strike as a Bonus Action.

You may use different weapons for different attacks as part of the same Attack Action. Although a very strict reading of this text may seem like you should have to use unarmed strike for all your attacks, I don't think that is how the rule was intended. For my interpretation, I am satisfied with any of the attacks triggering the availability of Martial Arts (since that would be a case of using your Attack Action to make an unarmed strike or attack with a monk weapon, regardless of what the other attack was used for).

While there aren't any restrictions on what the other extra attack can be, note that Monks cannot use Martial Arts while wielding non-monk weapons. This is not an opening for Monks to use heavy/two-handed weapons along with unarmed strikes. When holding a Halberd for instance, the Monk's unarmed strike would use Strength for the attack, deal 1+Str bludgeoning damage, and would not allow for using a bonus action to make an extra unarmed strike. (You would however still benefit from Unarmored Defense.)

Answer 3

Yes

I would argue you, in the most literal sense, "used the Attack action with an unarmed strike and a special melee attack (grapple)". Since this includes using the Attack action with an unarmed strike, you will have satisfied the requirement for the Martial Arts feature.

When you use the Attack action with an unarmed strike ... you can make one unarmed strike as a bonus action.

Answer 4

Yes you can

Note that Grappling is also an Attack Action:

When you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack, a grapple. If you're able to make multiple attacks with the Attack action, this attack replaces one of them.

The ruling in this case is if you are considered Grappling with an unarmed strike or a monk weapon (Definitely not unarmed strike). While not RAW, unless you can convince your DM you are grappling the target with your monk weapon, i would let the monk use Martial Arts with a single Grapple.

You don't grapple with a weapon - you grapple with "Using at least one free hand". A DM can house-rule anything, but this changes the fundamental grappling requirements.

– NautArch

Back to your question!

For the extra attack it's not specified for one or two attacks. So the trigger condition is either met or not.

"Did you attack with an unarmed strike or monk weapon?"

"Yes."

"You can use Martial Arts."