April 1, 1873

Today marks the 140th anniversary of the loss of SS Atlantic and 535* lives off Halifax. The tragedy was so unimaginable then, as it is now, that the first news of the ship's grounding was thought to be an April Fools prank. It was not.
The White Star Line ship (the second ship in the line) was built by Harland & Wolff in Belfast (later to build White Star's Titanic) in 1870 and regularly sailed between Liverpool and New York. It sailed on its last such voyage on March 20, 1873, stopping briefly in Queenstown on the 21st, under Capt. James Williams, with four deck officers also qualified as masters.
The ship's 600 hp engine was known to burn 55 to 60 tons of Welsh coal  per day, but her bunkers carried lower grade mixed coal on this trip, and had used some 80 tons before sailing from Liverpool, leaving 967 tons on board. On the 11th day of the trip it was calculated that they had been burning 70 tons per day, and had only about 127 tons remaining on board - not enough to reach New York. [I know this arithmetic is faulty, but that is what the later inquiry found.]
Since Halifax was the nearest port with coaling facilities, it was decided to put in for more.
On approaching Halifax at 0315 hours on April 1 the ship had wandered from her proper course and ran onto Meagher's (now Mars) Island off Terrance Bay, some 50 yards form shore, then fell on its side. Conditions were such that all boats were smashed in the surf and it was only by a crew man carrying a line ashore and sheer luck that more of the 952 (811 passengers, 141 crew**) aboard were not lost.
An inquiry found the master had left the bridge with instructions to be called at 0240 hrs, however the fourth mate did not make the call. The navigators had not allowed for a 1 knot current set (and dead reckoning errors) and were 12 to 13 miles west of the expected land fall. The inquiry found that on approaching the unfamiliar port, the watch officers failed to exercise proper vigilance, did not monitor the ship's speed, did not sound for depth, nor did they take notice of the established light stations at Sambro Island, Chebucto Head nor Devil's Island, all of which were lit and visible at the time.
The ship's master was found responsible and the mate charged with lack of vigilance. The master's certificate was suspended for two years, but would have been canceled outright were it not for his efforts to save lives following the wreck. 
*  exact numbers will never be known, but likely not more than 545.
** sources vary - these numbers are from the wreck inquiry. As with most accidents such as this one, the majority of the crew (131) survived. This may have been in part because many were awake and on watch, they were housed nearer the decks and were physically fit.