Theodore C. Maillet attended Livermore Falls High School in Maine, where, under the direction of coach John P. “Paddy” Davan he became an outstanding southpaw pitcher.

As a sophomore he pitched the high school team to the 1936 state baseball championship, and the following year he won 18 games, including two no-hitters in as many days against Wilton Academy and Winslow High. In his senior year in 1938 Maillet again pitched Livermore Falls High to the state finals where he was beaten, 6–0, by Lewiston High. He got Livermore Falls’ only base hit of the day.

Maillet was signed by the Cincinnati Reds following graduation and joined the Durham Bulls of the Class B Piedmont League late in 1939, appearing in two games and being credited with a win. He joined the Tyler Trojans of the Class C East Texas League in 1940, and finished the season with a 12–8 record and 3.41 ERA. In 1941, he was with the Columbia Reds of the Class B South Atlantic League, and was 4–3 in nine games before joining the Erie Sailors of the Class C Mid-Atlantic League where, in 18 appearances he produced an excellent 11–4 won-loss record with a 2.12 ERA. The Sailors finished second in the regular league standings — two-and-a-half games behind the Akron Yankees — then swept the Springfield Cardinals in three games in the playoffs and clinched the league title in five games against the Canton Terriers. Maillet defeated the Terriers, 5–2, in the opening game of the series, holding them hitless over six innings and allowing just three hits in the game. He then clinched the title for the Sailors in the fifth game with a 4–3 win in which he made an unusually high 11 assists from the mound.

Maillet, who had a 1-A draft classification, expected to be called for military service at any time following the 1941 season. Instead of joining the Erie club for the 1942 season, he chose to retire from baseball and took employment in defense work at the General Electric plant in Erie while awaiting his call. Maillet, however, did not hear from the
military all summer and played semi-pro baseball for local teams while working at General Electric.

As an indication of how popular Maillet was as a pitcher for the Sailors, he was convinced to come out of retirement on July 8, 1942, to rejoin the club in an exhibition game against the Cleveland Indians. In front of 3,000 fans at Erie’s Ainsworth Field, Maillet yielded four hits in the first inning which sent the Indians away to a five-run lead. He blanked the major leaguers on two hits during the next five innings, but a seventh-inning double by second baseman Ray Mack and a home run by shortstop/manager Lou Boudreau, which landed on top of the schoolhouse in right field, produced a pair of runs. The Indians came away from the contest as 10–1 winners.

Maillet remained at General Electric until entering military service on November 8, 1943. Serving with the 386th Infantry Regiment of the 97th “Trident” Infantry Division, he arrived in France in March 1945. On March 28, the division moved into Germany and crossed the Rhine River on April 5. Two days later the 386th Infantry Regiment crossed the Sieg River and faced counterattacks by German forces. Private First Class Maillet was killed that day. He is buried at the Ardennes American Cemetery in Neupre, Belgium.