21st President: Chester A Arthur, 1881

Net = 21 (Arthur was the 21st president)

King Arthur = Arthur

Theft = 881 = 1881 became president

Chest of an A = Chester A 

A net (21) was what the thief used to take the sword away. King Arthur (Arthur) spotted it and shouted "Theft!" (881 = 1881) to raise the alarm.

Connect Arthur to Chester A

King Arthur (Arthur) always admired the tattoo on his chest of an A (Chester A).

NOTE: The way Mammoth Memory remembers Chester is to think Chester has a big chest.