This bronze artifice, cast by the Bocarro family foundry in Macao, also known as the Miracle Cannon, was salvaged in May 1977 from the Shipwreck site of the Portuguese gallion Sacramento, which ran aground near Schoenmakerskop on her maiden voyage in 1647. It was declared a National Monument under old NMC legislation on 7 March 1986. Wording on English commemorative stone:

 
 
 
Wording on English commemorative stone:
 
DONATED BY
COMMANDER C J ALLEN
30 JUNE 1993
 
IN MEMORY OF PORT ELIZABETHAN DAVID ALLEN
AND DEDICATED TO THOSE WHO PERISHED
IN THE PORTUGUESE GALLEON SACRAMENTO
WRECKED ON 30 JUNE 1647
THE 72 SURVIVORS SET OUT TO WALK
THE 1300 KM TO MOZAMBIQUE
NINE PERSONS SURVIVED TO REACH
DELAGOA BAY ON 5 JANUARY 1648
 
THIS CANNON LENGTH 469 CM MASS 2500 KG
COVERS THE SITE OF THE WRECK
IT WAS CAST IN BRONZE BY BOCARRO IN THE
PORTUGUESE TERRITORY OF MACAO, CHINA
IN 1640 AND IS ONE OF 10 SALVAGED BY
DAVID ALLEN AND GERRY VAN NIEKERK IN 1977
 
Geolocation
-34° 1' 9.1155", 25° 19' 21.6495"
Further Reading
https://www.sahistory.org.za/franco/postal-history-PE-mainpost.html
https://www.sahistory.org.za/.../donkin-reserve-and-donkin-memorial-port- elizabeth
https://www.sahistory.org.za/place/port-elizabeth