"in the service of" vs "at the service of"

[Zague]

What expression would best describe the relation of a servant to a master or authority?

He is "in the service of" Dom Leon.

He is "at the service of" Dom Leon.

Thanks.

Z

[David L.]

The servant is 'in the service' of his master.

The servant would say, "I am at your service, sir." (ready to do his bidding.)

[Zague]

Thanks!

Just to make sure that I'm getting it right, what if it is the servant who speaks of himself in this fashion:

"I am Brother Emilio, a benedictine monk "in" the service of Dom Leon."

"I am Brother Emilio, a benedictine monk "at" the service of Dom Leon."

Z

[David L.]

"I am Brother Emilio, a benedictine monk "in" the service of Dom Leon."