Based on the Coast Guard Historian’s timeline, https://www.history.uscg.mil/research/chronology/
With inspiration from Mike Kelso

April 15

1909  The schooner G.A. Hayden grounded northeast of Station Point Judith. The sea being too rough for surfboat, the life-saving crew took the beach apparatus to the wreck and succeeded in reaching her with the second shot.  The first of her crew was landed in the breeches buoy at 12:10 am.  After 4 trips the last one came ashore at 12:45. The vessel was a total loss.

1986  The Libyan military, on orders from dictator Moammar Gadhafi, fired a missile at Coast Guard LORAN Station Lampedusa off the coast of Italy.  The missile fell harmlessly in the Mediterranean and there were no casualties.

April 16

USRC Louisiana

1820  Landing parties from the cutters Louisiana and Alabama destroyed a pirate base on Breton Island.

1908  Congress authorized the creation of the Office of Captain-Commandant and Engineer in Chief.  Additionally, commanding officers of vessels were authorized to administer oaths of allegiance and other oaths for service requirements in Alaska.

USS Joyce

1944  The Coast Guard-manned destroyer escort USS Joyce, along with her sister warship USS Peterson and a Navy DE sank the German submarine U-550 off New York.  The U-boat first torpedoed what was at the time the largest tanker in the world as the convoy it was joining was forming up outside of New York harbor.  The destroyer escorts then attacked the U-boat, forcing it to the surface, and then sank it in a surface gun-battle.  Joyce rescued the surviving u-boatmen as well as those off the stricken tanker.

Texas City disaster. Parking lot 1/4 of a mile away from the explosion.
Courtesy of Special Collections, University of Houston Libraries. To visit the entire collection at the University of Houston Digital Library please visit: http://digital.lib.uh.edu/cdm4/results.php?CISOOP1=exact&CISOFIELD1=CISOSEARCHALL&CISOROOT=/p15195coll4&CISOBOX1=Texas+City+Disaster&CISOSTART=1,1

1947  The French-owned Liberty ship Grandcamp exploded while loading ammonium nitrate at Texas City, Texas in one of the worst peace-time accidents ever to occur in a U.S. port.  Over 500 died and thousands were injured.

By U.S. Navy – United States Naval Operations Vietnam, Highlights; June 1966 – Map – U.S. MARKET TIME Forces, Public Domain, https://commons.wikimedia.org/w/index.php?curid=34475896

1965  Secretary of the Navy Paul Nitze asked Secretary of the Treasury Henry Fowler for Coast Guard assistance to combat seaborne infiltration from North Vietnam.  This naval operation in Vietnam was named Operation Market Time.