Is allusion is a way to compare history with the current subject of the poet?

Yes an allusion is something to compare the history with the subject of a current poet.

Allusion is a figure of speech, in which one refers covertly or indirectly to an object or circumstance from an external context.[1] It is left to the audience to make the connection; [2]where the connection is directly and explicitly stated (as opposed to indirectly implied) by the author, an allusion is instead usually termed a reference.[3][4][5] In the arts, a literary allusion puts the alluded text in a new context under which it assumes new meanings and denotations.[6] It is not possible to predetermine the nature of all the new meanings and inter-textual patterns that an allusion will generate.[6] Literary allusion is closely related to parody and pastiche, which are also "text-linking" literary devices.[6]

In a wider, more informal context, an allusion is a passing or casually short statement indicating broader meaning. It is an incidental mention of something, either directly or by implication, such as "In the stock market he met his Waterloo."