'To close upon' definitions:

Definition of 'To close upon'

From: GCIDE

Close \Close\, v. i.
1. To come together; to unite or coalesce, as the parts of a wound, or parts separated. [1913 Webster]
What deep wounds ever closed without a scar? --Byron. [1913 Webster]
2. To end, terminate, or come to a period; as, the debate closed at six o'clock. [1913 Webster]
3. To grapple; to engage in hand-to-hand fight. [1913 Webster]
They boldly closed in a hand-to-hand contest. --Prescott. [1913 Webster]
To close on or To close upon, to come to a mutual agreement; to agree on or join in. "Would induce France and Holland to close upon some measures between them to our disadvantage." --Sir W. Temple.
To close with. (a) To accede to; to consent or agree to; as, to close with the terms proposed. (b) To make an agreement with.
To close with the land (Naut.), to approach the land. [1913 Webster]