''Not half so fixed the Trojan could remain, While Anna begged and Dido raged in vain'' is example of _

Allusion is an implicit or indirect reference to another work of literature, a historical or mythical person or event.
Examples:
- ‘The winged boy I knew;
But who wast thou, O happy, happy dove?’
(Keats: “Ode to Psyche”)
The “winged boy” is an allusion to Cupid, the god of love.
- ''Not half so fixed the Trojan could remain,
While Anna begged and Dido raged in vain'' is another example of allusion.
(Pope: The Rape of the Lock)

Source: An ABC of English Literature - Dr. M Mofizar Rahman.