Cover art
Scott, Melissa, and Lisa A. Barnett. Armor of Light. Baen 1988.

Scott, Melissa, and Lisa A. Barnett. Armor of Light
Divergence: 1586 CE
What if: Witchcraft works. Also, Sir Philip Sidney survived the battle at Zutphen.
Summary: In 1593, Elizabeth I directs Sidney and Christopher Marlowe to protect James VI/I from magical attacks.
Published: Baen 1988 (0671697838BUY); NESFA 1997 (0915368293BUY).