Arniel, 55, joins Washington after spending the past five seasons as an associate coach with the New York Rangers. Arniel brings more than 15 years of professional coaching experience, which includes serving as head coach for the Columbus Blue Jackets from 2010-12. In addition, the Kingston, Ont., native compiled a 218-136-21-21 record in five seasons as head coach in the American Hockey League with the Chicago Wolves and the Manitoba Moose. Arniel guided the Moose to the Calder Cup Finals in 2009 after posting franchise records with 50 wins and 107 points to finish atop the AHL standings. Arniel captured the Louis A.R. Pieri Memorial Award that season as the AHL Coach of the Year.

Prior to joining the coaching ranks, Arniel appeared in 730 NHL games with the Winnipeg Jets (1981-86; 1990-91), Buffalo Sabres (1986-90), and Boston Bruins (1991-92), registering 338 points (149g, 189a) in 11 seasons. Arniel was originally selected by Winnipeg in the second round, 22nd overall, in the 1981 Entry Draft. Arniel and his wife, Lia, have a son, Brendan, and a daughter, Stephanie.

Cashman, 35, spent the past two seasons as an assistant coach with the Hershey Bears. In Cashman's first season behind the bench in Hershey, the Bears finished fourth in the AHL in shots against, and advanced to the second round of the Calder Cup Playoffs.

Cashman joined Hershey in 2016 after a successful tenure at Quinnipiac University. Cashman, a Minnesota native, coached at his alma mater for six seasons prior to joining the Bears. At Quinnipiac, he spent four years as an assistant coach, and two as an associate head coach, helping lead the Bobcats to the Frozen Four in 2012-13 and 2014-15. The Bobcats were 129-48-28 during Cashman's tenure. As a player, Cashman was a three-time All-American defenseman at Quinnipiac, graduating in 2007. He then played five seasons professionally with the Columbia Inferno in 2007-08. He won the Kelly Cup with the Cincinnati Cyclones in 2010, and skated in 68 career AHL games with Toronto, Wilkes-Barre/Scranton, and Milwaukee.