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It was to be the biggest planned explosion in the history of mankind. Officials were nervous. Some people feared the blast would destroy the entire Seacoast -- perhaps start a chain reaction that might end the world. But Henderson's Point was a hazard to navigation, and President Teddy Roosevelt wanted a big navy, the biggest in the world.

The age of sail was dead, and Portsmouth Naval Shipyard, already over 100 years old, was going to build new-fangled high-tech ships and submarines. The Yard was expanding, modernizing, getting ready for its large new drydock. So the outcropping of land extending from Kittery, Maine toward New Castle, NH was blown to silt on July 22, 1905.

This was also the year of the Treaty of Portsmouth between Russia and Japan, a big era for military might and a feather in the cap of Roosevelt. Portsmouth was the region that had produced John Paul Jones’ ship Ranger and the USS Congress, sister ship to the Constellation and Old Ironsides. Admiral Jones' body had just been discovered in Paris, and naval fervor had gripped the country. Here's the story if the blast in pictures, collected into a 1905 souvenir postcard series. The series includes two photos, including one of the actual explosion, and three superb drawings by our own Helen Pearson, best known for her penciled "Vignettes" of Portsmouth.

Scroll down and read the captions, then click to the next page to see the "blow-ups" of each image as the explosive story unfolds. Thanks to Debbie Wilson for scanning these images from her collection. Illustrations by Portsmouth artists Helen Pearson.

BONUS: see original postcard plate blcok

Henderson's Point before commencing work. Peirce Island is in the foreground, just off what today is Prescott Park. Back at the turn of the 20th century, this area off Water Street was a rough seaport area. Local sailors knew the point better by its more colorful name -- Pull-and-be-Damned.

A view from "up river" side showing the cofferdam prior to the explosion. The wooden dam allowed the preliminary removal of material using railroad cars before the dynamite did its work. The federal project was budgeted at $749,000 and awarded to a Massachusetts firm that was required to remove 220,000 cubic yards of rock and 50,000 cubic yards of soil.

Last overview of Henderson Point before the explosion from a drawing by artist Helen Pearson. The explosion was planned to remove a 540 foot rock projection to the depth of 35 feet. Twenty-seven drills were required to set the explosives in what was to be, at the time, the largest explosion ever attempted by man.

Now we switch to a photograph in the 1905 postcard series showing the height of the wall on the land side just before the explosion. Bye, bye Henderson's Point.

Kaboom! Henderson's Point exploded on July 22, 1905 in this extraordinary early photo by R H Foss. Debris flew 170 feet into the air. Although the river dredging was not completed until 1912, the Piscataqua was busy with boats only minutes later as curious onlookers found the river to the sea widened by 350 feet in seconds!

SEE MORE actual photos of explosion and before & after

CONTINUE Larger Postcards of Henderson's Point 1906