Avengers (1963) #273

"Rites of Conquest!"

As recounted in Amazing Spider-Man #283, while the main force readies their assault, Baron Zemo gives Absorbing Man and Titania (Mary MacPherran) a side mission to meet up with another incoming operative at LaGuardia Airport. They never make their intended rendezvous with their "mystery associate" (later revealed to be Mongoose) thanks to the intervention of Spider-Man (Peter Parker).

After months of planning and surveillance, Zemo's new Masters of Evil storm the Avengers' mansion and take Jarvis captive.