What was an informal agreement a year ago between the Charleston Battery and Major League Soccer's Vancouver Whitecaps FC has now become an official partnership between the two soccer clubs.

The Battery and Whitecaps announced Thursday they have agreed to an initial one-year affiliation.

As part of the deal, the Whitecaps will loan a minimum of four players from their MLS roster to the Battery during the 2014 USL Pro season. As a result, Vancouver will not participate in the MLS Reserve League in 2014.

A year ago, the Battery's roster featured three players with ties to Vancouver. Midfielder Bryce Alderson, U-23 midfielder Ben Fisk and U-23 fullback Emmanuel Adjetey each spent time on loan with the Battery in 2013.

"We had an informal agreement last year that I think worked out very well for both clubs," said Charleston Battery coach Mike Anhaeuser. "We've been talking with Vancouver since the end of the season and I'm excited that we were able to work things out and get something formal in place. I think this is a partnership that's going to benefit both clubs."

Despite being more than 3,000 miles apart, the Whitecaps and Battery have a long history together while both were members of the United Soccer Leagues from 2001-10. It's that previous relationship in the USL that made the affiliation a natural progression for the two clubs.

"The Battery is a well-respected club with a tradition of success on and off the pitch," said Whitecaps FC president Bob Lenarduzzi. "We have a long-standing relationship with (Battery president) Andrew Bell, dating back to our days in the USL First Division, and we are excited to formalize an official partnership.

"This affiliation will greatly benefit the development of our younger players by providing an opportunity for them receive more minutes in a professional environment, and as a result it will help with player transition from our Residency and U-23 programs into the first team."

The distance between the two clubs could have its pluses and minuses, Anhaeuser said.

"If Vancouver gets a couple of knocks and needs a player quickly, then, yes, the fact they we're 3,000 miles away could become an issue," Anhaeuser said. "But that doesn't happen that often. If a player gets hurt and he's not available, you usually know a few days in advance. On the positive side, since we're so far apart, it usually means the players that are here will be here for a good portion of the season."

Anhaeuser said the Whitecaps could even send the Battery one of their top players on a rehab assignment.

"Last year there were some discussions about sending us one of the top 11 guys because he wasn't match fit and needed a game or two before he could get back into their lineup," Anhaeuser said. "I could see that happening, especially if we're on the West Coast."

The exact number of players and who will be assigned to Charleston will be determined as the season gets closer, Anhaeuser said. A year ago, Adjetey played the most games in Charleston (22) among the three Vancouver players. In an injury-plagued season, Fisk had two goals and three assists with the Battery in eight games, while Alderson had an assist in 14 games.

"I think that's something that we'll work on together," Anhaeuser said. "The players that they send here want to get as many games as possible so they can develop. We want them to come here and be a part of the team and work on eventually making it to the MLS."

The deal leaves only three USL PRO clubs - Charlotte Eagles, LA Blues and Phoenix FC - without an affiliation agreement.

MLS clubs affiliated with USL PRO clubs are Columbus (Dayton Dutch Lions), D.C. United (Richmond Kickers), Houston (Pittsburgh Riverhounds), New England Revolution (Rochester Rhinos), Philadelphia (Harrisburg City Islanders), Portland Timbers (Sacramento Republic FC), San Jose Earthquakes (Sacramento Republic FC), Sporting Kansas City (Oklahoma City Energy, Orlando City), and Toronto FC (Wilmington Hammerheads).