On this day, April 22

1794 Pittsburgh was incorporated as a borough.

1864 Congress authorized the use of the phrase “In God We Trust” on U.S. coins.

1915 The first full-scale use of deadly chemicals in warfare took place as German forces unleashed chlorine gas against Allied troops at the start of the Second Battle of Ypres in Belgium during World War I; thousands of soldiers are believed to have died.

1960 The afternoon Sun-Telegraph was purchased by the Post-Gazette.

1988 The University of Pittsburgh named its Center for International Security Studies after Gen. Matthew Ridgway.

2004 Army Ranger Pat Tillman, who had traded in a multimillion-dollar NFL contract to serve in Afghanistan, was killed by friendly fire; he was 27.

Some items are from Stefan Lorant’s “Pittsburgh: The Story of an American City” (digital.library.pitt.edu/chronology).

— Compiled by Rick Nowlin

Today’s birthdays: Actor Jack Nicholson, 84. Singer Mel Carter, 82. Author Janet Evanovich, 78. Country singer Cleve Francis, 76. Movie director John Waters, 75. Singer Peter Frampton, 71. Rock singer-musician Paul Carrack (Mike and the Mechanics; Squeeze), 70. Actor Joseph Bottoms, 67. Actor Ryan Stiles, 62. Baseball manager Terry Francona, 62. Comedian and entertainment executive Byron Allen, 60. Actor Chris Makepeace, 57. Rock musician Fletcher Dragge, 55. Actor Jeffrey Dean Morgan, 55. Actor Sheryl Lee, 54. Actor-talk show host Sherri Shepherd, 54. Actor Eric Mabius, 50. Actor Ingo Rademacher, 50. Rock musician Shavo Odadjian (System of a Down), 47. Rock singer-musician Daniel Johns (Silverchair), 42. Actor Malcolm Barrett, 41. Actor Cassidy Freeman, 39. Actor Michelle Ryan, 37. Actor Zack Gottsagen, 36. Actor Amber Heard, 35. Singer-songwriter BC Jean (Alexander Jean), 34. Drummer Tripp Howell (LANCO), 32. Rapper/singer Machine Gun Kelly, 31.

Thought for today: What’s vice today may be virtue, tomorrow.”

— Henry Fielding, English novelist (born this date in 1707, died in 1754)