The Cunard Line was begun by Samuel Cunard in 1840 as the North American Royal Mail Steam Packet Company, though always known as the Cunard Line.
Using four small, wooden steam-paddle driven ships named Britannia, Acadia, Caledonia and Columbia, Cunard's goal was to provide a regularly scheduled steam mail service across the Atlantic offering weekly departures. This would be a dramatic improvement over the sailing packets of the day who only sailed when weather and business conditions were most favorable. It would also provide a strong lead for England as a sea power since the Americans had been slow to accept steam as a means of crossing an ocean - though America was using steam on river and inland waters regularly.
These first ships could cross the Atlantic in just over 11 days. These four ships began, what was to become, over of 100 years of leadership and constant competition to all who tried to operate service between the continents. Cunard's dream was to operate a weekly service using only two grand liners. This wasn't realized until after WWII when the Queen Elizabeth joined the Queen Mary in trans-atlantic passenger service; a plan that was laid down roughly 20 years prior.
The late 40's and 50's belonged to the two Queens. Even the loss of the speed record to the S.S. United States didn't seriously damage their dominance of the Atlantic. It would take the jet airliner and the 60's to end trans-atlantic service as a means of travel. Today, only QE2 offers Atlantic crossings intended to please the traveler with leisure as a goal.
Some of the most notible ships in the fleet included . . .
Campania 1893 - 1914
Lusitania
1907 - 1915 (Photo from actual postcard mailed on board 1908)
Aquitania 1914 - 1950
Queen Mary 1936 - 1967
second Mauretania 1939 - 1965
Sylvania 1956 - 1968
These lovely and amazing ships have a great deal of history attached to them. You can read more at the sites noted on the main home page of Ocean Liner Resource.