Cullinane College also made the nationals after finishing runnerup to WHS at Central.
"Its exciting to see the talent we have here in Wanganui," said Brown.
Cullinane would ultimately finish eighth overall, beaten by Massey High School 5-3 and Te Awamutu College 6-4 in their playoff games.
WHS started Day 1 with wins over Massey (6-4), St Andrews College (7-2) and Kaikorai Valley College (8-2).
They met Mt Albert on Day 2 and stumbled 5-4, before beating townmates Cullinane 6-4 and then avenging their 2013 final defeat to Alfriston, 7-4.
An 8-2 win followed over Rutherford College, before beating Macleans College 5-4 in the Cup semifinals.
Team members Blair Osborne, Kalib Houltham, Ruhia Tamati and Taniko Tamehana made the mixed-grade tournament team.
Osborne and Tamati were recognised as the boy's and girl's MVPs of the entire grade.
"This was absolutely amazing to have two players recognised Most Valuable of the tournament, plus to be both Year 11," said Brown. "Shows the potential for the next few years."