June 15 (Reuters) - Defense startup Mach Industries has raised $5.7 million in a seed round led by Sequoia Capital, the first-ever defense tech investment in the venture capital giant's history, the two companies said. Sequoia's funding of a technology that aims to use hydrogen creation on the battlefield signals the latest interest from Silicon Valley investors in backing technologies that bolster U.S. national security and working with the Department of Defense. "There is a technology transition happening, and recent events like the war in Ukraine have highlighted the gap in current defense systems," Shaun Maguire, a partner at Sequoia...