Connections

Poul Anderson wrote several linear series but also perfected the technique of obliquely interconnecting his works of fiction. Of the following works:

The Golden Slave
The King Of Ys Tetralogy (with Karen Anderson)
The Broken Sword
The Demon Of Scattery (with Mildred Downey Broxon)

- the first is a historical novel set during the Roman Republic;
the second is a historical fantasy about the last days of the city of Ys during the decline of the Roman Empire;
the third is a historical fantasy that refers to drowned Ys;
the fourth is a story told during a journey made in the third, The Broken Sword.

Of the following four fantasy novels:

Three Hearts And Three Lions
Operation Chaos
Operation Luna
A Midsummer Tempest

- Holger Danske appears in two, Valeria Matuchek appears in three and they meet in the inter-cosmic Old Phoenix where other characters meet in two short stories. Thus, although Operation Luna is a direct sequel to Operation Chaos, the quartet as a whole is more many-sided than, eg, if Anderson had simply written four Operation volumes.